When did your wife become opposed to the idea? Was it after you were married? 

There are women AND men who agree they want more children with their partner.... until they get the ring on that partner's finger. Then the baby agreement fades away.

My apologies for being blunt, but it sounds like your wife may have been looking for a substitute father for her children (you call the bio dad absolutely worthless). 

If you really want a biological child, you need to consider if this deal-breaker. Would you have married her, knowing she didn't want more children when you DO?

You have some thinking to do.

I left my first marriage in part because my XH made the decision that he didn't want kids. What he did was unfair to me knowing I wanted kids. What your wife is doing is unfair to you knowing that you want kids.

So, I don't have words of encouragement except encourage you to really look at your marriage and figure out if your want for your own kids trumps your want to be with your wife, and if it doesn't now, will you build up resentment towards her as time goes on?

As a dude, you have A LOT of years left with good sperm. You can also look at banking your sperm for a relatively small fee. If you really want kids of your own, you have time and options.

This is the ultimate bait and switch. "Wonderful" people don't do that to you. It's Unconscionable. It's grounds for an annulment if you haven't been married long. Do not give up something that means so much to you. Find someone who wants to be with you fully and create a family with you. This is her family - not yours. 

Your DW may only have a few years left to decide, but you have a good 15-20 years. I can't imagine sacrificing having my own in exchange for 3 skids with a worthless BD (you say you have to share the youngest, are there 2 BDs?)

In any case, you are not trapped. You can still change your mind. 

Dup

Bait and switch is apparently very common in steplife.

I feel that was completely unfair of your wife to suddenly change her mind, after marrying you, KNOWING you wanted a child of your own.

Time to really consider if this is the person for you.

If the BD is worthless and there are 3 children involved, chances are that she was looking for a good dad for her children and told you what you wanted to hear with the intention of "oh well, he will understand. He will fall so in love with my wonderful kids, that he will accept them as his own and wont want any of his own."

I myself have had a few people tell me "how fortunate you do not have children of your own, so you can give your time and resources to HIS kiddo."

BS on that!

Yeah, that's crappy. She said what she had to say to get you to sign on the dotted line, then reversed. While I can certainly see why she might not want a 4th kid, she should have said while you were dating.

due to their age and no kids would want kids (a normal progression of marriage), claims i’m defini Open to it... there is no “definitely open to it”. Either you are or aren’t!!

my husband had been divorced 5.5 yrs when i met him and skids were 18, 15 and 8 at the time and the 2 sd’s aged 18 & 8 hd ceased contact with daddy about just over a year prior and only re-initiated contact over 5.5 yrs later.

hubby knew me being a 28 yr old would want kids and he was ok with that. He wanted them with me too. He knew it wasn’t fair to do the bait and switch thing because its selfish. One of his bosses wants this as a stipulation for marrying and my husband is 100% against that saying people like this have no business destroying someones life by lying to them or leading them on.... essentially he wants the sex, no kids despite the woman wanting some...

whether you think you can talk this through but don’t fall for ok we can try and meanwhile she is on birth control and trying to sabotage a pregnancy. You need to be blunt and tell her you married me under false pretenses and i’m not ok with that and tell her you will be seeking an anulment. 

She can claim she will sue you for alimony and blah blah blah but its steam. She lef you on and a judge will see that.

don’t waste your time with fake people..

I am 34 and pregnant with my first. Before DH and I got married we talked about kids and how I would possibly want to try. He said he would think about it and consider. After we got engaged and I spent more time around SS11 (now DS) I decided I wanted to try for my first Bio. I told DH I would not marry him if he could not agree. He said possibly before we got engaged and bought a house together both our names on it and then decided that he did not want another child. I flat our said well than I will leave.

It was back and forth discussion with us alot, eventually he gave me what I wanted. We are both in our early 30's as well. We will have one in his senior year of high school and one starting school in a few years big age gap. I understood my DH perspective about having to start over and do it all agian but I explained to him that I really wanted to do it fromt he beginning. I want to know what it is like to hear moma for the first time and only ever be known as that. I wanted to know what the kind of bond felt like. Do not get me wrong I love my DS very very much. We have a pretty great relationship, minus he is total pre-teen right now. I cherish the bond we have as it is something different we both have had to earn that love we have given one another.

Talk to your wife and explain to her your reasons for wanting another child at least one that is biologically yours. In all honesty if she does not change her mind and still says no I see some major resentment in your future. It sucks to be told one thing and trust it and be taken from you. I really thought that is what my DH was doing to me at one point. We talked and figured it all out. Honestly he is really excited about having another boy now.