When Mike Brady married his fiancée, Carol, his three sons and her three daughters united to become television's famous Brady Bunch.

If they were forward-thinking, they would have discussed how the blending of their two families would affect their finances – present and future.

Blended families – in which one or both of the partners bring children from a previous relationship – face unique social and psychological challenges, which intertwine with the family's finances.

"This is hard," said Norman Lofgren, an estate-planning attorney at Looper Reed & McGraw in Dallas. "When you have a blended family, you have all sorts of dynamics and a lot of unspoken agendas."

ROBERT NEUBECKER/Special to DMN

Spouses in blended families anguish over trying to provide for their partner, their own children from a previous marriage, the spouse's children from a previous marriage, and in some cases, children that they've had with their partner. Mr. Lofgren said.

"They're trying to balance these competing interests," he said.

It's something that more people will be dealing with, as blended families are expected to keep growing, experts say.

"Blended families now outnumber traditional nuclear families, and the number is likely to grow, based on current divorce statistics and trends," said Jay A. Rose, an estate planning lawyer in Woodland Hills, Calif.

Generally, spouses who have kids from a prior marriage want to try to protect those children, "sometimes to the exclusion of the new spouse's children from another marriage," he said.

"The challenges are [that] after they remarry, they accumulate assets together, and the conflict comes up on the death of both spouses. How are those assets divided among the children and their children from different marriages?" Mr. Rose said.

But there are financial issues that must be addressed way before either spouse dies.

"The main problem is going to be the kids' expenses," said Steven Buholz, a Dallas family law attorney, who formed a blended family with his wife, Vicki, and her two boys. He also has two grown children. "The costs of adding a new stepchild to one's relationship can be significant. You get into everything from band lessons to music lessons to camp to birthday parties. It's all these little incidentals."

If there's child support and alimony involved from a previous marriage, those must be discussed.

"Many remarried couples with children either pay or are paid child support for a designated period set by their prior divorce agreements," said Rick Salmeron, a certified financial planner at the Salmeron Financial Network in Dallas. "Couples should discuss how this would impact the blended family."

For example, when a stepchild's everyday expenses or major needs such as health care and tuition need to be paid, and the alimony or child support isn't enough, "this can be sticky," he said.

"If one remarried spouse makes less than another, the idea of 'you pay for your kid, I'll pay for mine' can become troublesome," Mr. Salmeron said. "The remarrying couple might want to consider bringing their ex-spouses into the picture and possibly drawing up some formal agreement with them if these issues are not addressed in their current divorce and child support settlements."

While he gladly takes on the duty of supporting stepsons David, 12, and Daniel, 11, Mr. Buholz said couples forming blended families must realize it will require adjustments and to prepare for them.

It's especially important that couples in a blended family meet regularly to review expenses, Mr. Buholz said.

He follows his own advice.

"We do have a weekly meeting, and we talk about expenses that are fixed and that are expected every week," Mr. Buholz said. "Then we go through the unexpected expenses that everybody gets. You discuss it as a family and you get over the fact that sometimes it's a crisis, and then you must engage the situation with your plan of action."

The couple also must reconcile their different money-management styles.

"Most people can carry a backpack of insecurity and distrust left over from the separation of assets at the end of their prior marriage," Mr. Salmeron said. "Most of all, they now have their own way of doing things."

Added Mr. Buholz: "With a new spouse, you run into a situation where it's 'my money' and 'your money,' and you haven't lived together long enough to have 'our money.' You have your own two kingdoms that you're combining."

What's more, he said, "You have expenses that you as a single person have been accustomed to paying, but you now have immediate expenses that are common – life insurance, car insurance, mortgage, rent, health expenses."

You also need to sort out existing debts and address these questions:

•How much does your spouse owe and to whom?

•How will these debts be paid off?

•How does your spouse handle credit cards?

•What are your financial obligations to others? In addition to child support and spousal support, is there money promised to Grandma to provide for her in her old age?

By far, the most sensitive financial issue that couples in a blended family face is how to pass on their assets after they die.

Sometimes, this can unearth hidden resentments.

"Kids may view the stepmom as the impediment between them and the inheritance," Mr. Lofgren said. "It's ugly. How do you deal with all the competing interests, even if the kids are all adults?"

Conversely, a spouse may feel a stepchild isn't as entitled to inheritance as the child may think he or she is.

With a traditional family, "one dynamic that you don't have is if Dad dies, Dad can be fairly confident that Mom is not going to do anything to disadvantage Mom's own child, but if it's a stepkid, the new mom can say that kid's always been a brat," Mr. Lofgren said.

Of course, it isn't this way for all blended families.

Mr. Buholz doesn't anticipate those tensions when he and his wife discuss how to divide their assets among their children.

He and Mr. Lofgren said couples must talk about the issue, however uncomfortable it might become.

"You have to protect your kids, as well as protect your spouse," Mr. Lofgren said. "Just make sure you've got it all balanced and have everything tightened up. If you leave it to happenstance, you will have chaos down the road."

One vehicle a couple can use to equalize things is an irrevocable life insurance trust, experts said.

It's set up for the purpose of owning a life insurance policy on the life of either spouse. The proceeds of the policy are distributed to the beneficiary on the death of the insured.

"Life insurance is one way for a spouse to try to be fair to the extent that he or she wants to be fair to my spouse and be fair to my kids," Mr. Lofgren said. "You can control the way the proceeds are used."

For example, you can use the insurance benefits to provide for your spouse and then use your other non-insurance assets to provide for your children, he said.

The trust also provides tax protection.

If you're the owner of your life insurance policy, the proceeds will be subject to estate tax when you die. But if you transfer ownership of the policy to a life insurance trust, the proceeds are protected from estate tax.

Another method you can use to make inheritance rights more equitable among biological children and stepchildren is to state in your will or trust document that your stepchildren should be treated "as if they were a child of the parent who is not related to them," Mr. Lofgren said.

"That will put the child on equal footing with the other children in terms of inheritance rights," he said. "You define the word 'children' and the word 'descendents' to include the stepchild."

Discuss details with older children, said Mr. Salmeron, the financial planner.

"If your children are mature enough, tell them the details of your expected financial plans," he said. "They're more likely to support the new marriage if they know you've taken steps to protect their inheritance."