When a man marries a woman with a child(ren) from a previous marriage or relationship, the man becomes a stepfather. He also enters into a potentially complex set of relationships. In fact, every relationship he has in this stepfamily is going to complex.
With his new wife, it will be complex becuase he does not have equal parental standing with the children. In her life, they pre-existed him, thus giving him an historical disadvantage - they have more history with the mom than he does. She still needs to be the one in charge of the kids, which may feel all wrong and conflict with what many people call being the "man of the house." As a marital partner, he is an equal, but as a parenting partner he is not.
His relationship wth the stepchildren is complex because he a new man in the family. Furthermore, his love and affection and strength of commitment wit the children's mother earn him little or no credit as an authority in the realm of parenting. However, if he treated his new wife (the kid's mother) poorly, it would most certainly count against him so far as the kids are concerned and would probably be his ow undoing.
His authority as a parent is complex because he has little or no history with teh children, the children have a biological father (unless he is deceased) who fills an authority role (either real or imagined ) with the children. In fact, even if the bio father is deceased, in the kid's minds, he may still be the authority.
A stepfather's authority comes in two ways over a long period.
1.
Earned. When a stepfather shows himself patient, reliable, good, and willing to develop a relationshp with the stepchildren, these children may grant him some authority in their lives. This may seem all backwards, an adult working to gain authority from the kids. It may feel like the tail is wagging the dog. But if you think about it, it makes good common sense.
If you think about entering stepfathering not as a father figure, but rahter as a new man who is entering ther children's life, getting to know them, learning about them, like a new babysitter or baseball coach, then it makes a little more sense. A trust has to be built and a pattern of relating has to develop. The powerful and sensitive flow of wills must merge. that kind of thing seldom happens quickly.
2.
Bestowed. The mother must give authority to the stepfather. Although the temptation here is to do this all at once, it only works if it is done gradually. This does not happen in one sit down conversation with teh kids.
"Kids, darryl is your new stepfather and i give him all parental authority in the house. What he says goes."
You can say these words, but it won't do any good.
This kind of authority comes in little chunks and pieces, here and there. Bestowing authority upon the stepfather from the stepmother takes a very aware and alert set of parents. She really has to know her children's tolerance for the stepfather's inluence and he needs to be aware of the signs the kids give whe they are accepting or rejecting his authority and furthermore, have the courage to back off when he has violated that tolerance. Mom needs to be ready at anytime to bring her authority back into the picture if things are falling apart between stepfather and stepchildren. She cannot abdicate her authority - ever.
Again, this is very challenging to the sense of being "man of the house." It feels like everyone in the house has power to make things happen except the stepfather. "What am I, chopped liver?" might be the feeling of the stepfather when he has to earn authority with children and wait for it to be bestowed upon him from their mother. "Don't I have any authority just for being there?" "Hey, I bailed your mother out of a real financial bind, and this is the thanks I get?" Again, he earns no authority points by being a good husband.
Think big picture and think slow cooking here. Stepfathers can have a good relationship with their stepchildren, but it develops slowly and is always a work in progress. it is like an invesment into a 401(k), put a lot in with nothing to show for it, that is until it is time to cash in - and that time is not right now. It's worth it even if it is doing me no real good today. It's worth it for it's future value.