Dear Mr. Dad: I am getting remarried in a few months. I have two teens, 12 and 15, and my fiancé has custody of his 14-year-old. We will be moving to a new house to start our lives together as a family. Any advice on how to make this transition as smooth as possible?

A: Welcome to the wonderful world of blended families. And you certainly aren’t alone. In fact, one in three Americans is a stepparent, stepchild, stepsibling, or other member of an extended stepfamily.

Combining two families into one requires careful planning, open communication, and lots of patience. So if you’re fantasizing that your new brood will be just like “The Brady Bunch,” you’re about to find out that real life is not quite that rosy.

For starters, each member of your new family will be moving in with his or her own emotional baggage. The children might still be harboring unresolved anger stemming from the divorce or the death of their other biological parent. Treading gently and with utmost sensitivity is essential.

Here’s another challenge: You and your future husband will not be starting your lives as carefree newlyweds. Instead you’ll have an instant family and very little time or opportunity to focus on building your relationship. This doesn’t meant that you’ll have less of a marriage, just that you’ll have to find creative ways of nurturing your marriage. And don’t worry that you’re being selfish. You’re not. Having a strong and loving marriage will benefit the kids in the long run.

How quickly the children adjust to the new family structure depends on a number of factors. As a rule, the younger they are the easier it is for them to accept and embrace change. But just because your kids are slightly older doesn’t mean you have a rough ride ahead. Involve them in as many decisions as possible and appropriate. Talk about how each of you envisions the new life; point out the difficulties that might arise and how you propose to tackle them; ask for suggestions to make the transition easier. Most important, make sure they know that you’re all in it together and will find ways to work out whatever problems come up.

Find out what the children’s fears and concerns are, and, if you can, reassure them. One thing you and your fiancé should do right now is talk to your respective soon-to-be stepchildren and let them know that you will never try to take the biological parent’s place. Also remind them (you’ll have to do this many, many times) that it’s okay if they don’t all of a sudden love their stepparent or stepsiblings. Expecting them to is completely unreasonable. Love, if it happens at all, takes time. While you’re waiting, you may have to settle for mutual respect and “like.”

Before you include the children in the discussion, you and your future husband should decide what role each of you will have in raising your respective kids. For example, even though a new stepparent might be eager to jump right in and ingratiate him/herself with the stepchild, take it slow and easy. Let the biological parent control and discipline his/her kids, at least until the stepparent has developed a solid bond with them. While each of you will, at least initially, monitor your own children, make sure everyone is treated equally and fairly, without favoritism. Last thing you need is conflict and rivalry

You should also establish a list of household rules. Discuss them with the children and ask for their input. While you’ll likely be the enforcer and the disciplinarian, the kids should feel they have a role and a place in this new family. This is especially important with pre-teens and adolescents, who are notoriously oppositional even in traditional family units. Excluding them from the decision-making process might fuel an outburst of rebellion.

Finally, keep the number of a good family counselor handy. If, despite all your efforts, problems arise, a little professional advice may help you smooth out the glitches and build strong and lasting “blended” relationships.