Cue Auteur's list...

First, make sure that none of the below are going on before you take such a big step.
Read this and then think "more than one? RUN!"

1. Does your man allow co-sleeping with his children? (aka the kiddies routinely jump into bed with him at night)

2. Does he have to lie down with them to get them to sleep?

3. Do the children seem somehow "stunted" socially? Do they have poor hygiene habis, eating habits, bedtime habits?

4. Does your man subscribe to the "one big happy family" model? (expects you to love his children as much as or more than him)

5. Does your man have the "inability" to say no to his children?

6. Do his children seem overly "hyperactive" to you?

7. Does your man say "just relax; you worry too much" or "Everything will be just fine" if you bring up a legitimate concern

8. Do the children seem "overly needy" demanding that dad spend 24/7 with them? Do they physically lay all over him and go bonkers when daddy steps out of their peripheral vision?

9. Are they unable to do age appropriate tasks or want dad to do things that could easily be done themselves?

10. Does dad seem overprotective of his children; unwilling to let them try things out on their own?

11. Has dad said things like "I don't want to make waves with the BM b/c it will affect the children" or "we'll take the high road" when faced with blatant BM stepping over boundaries.

If you can answer YES to ANY of these questions, get your sneakers ready to go.

Do you know your man's FINANCIAL situation? Do you know if he has massive left over marital debt? How high is his CS obligation? Have you seen the divorce decree or mediation agreement. Does it seem overly slanted in BM's favour?

Love and "understanding" simply does not cover it all. Especially in the case of stepmom is supposed to be "understanding" when all of her money goes to household expenses b/c almost all of biodad's money goes to CS.

How long would you be willing to float biodad should he lose a job and have massive CS obligations?

There are many other considerations as this type of relationship is not to be taken lightly.

You need to talk to all the people on here that moved to another state and what a disaster it turned out to be before you start packing. They gave up their families, lives, homes and careers for someone that only used them for their advantage.

Thats a huge commitment moving states. I agree with AA, I think you need to find out a bit more about the situation before packing up and leaving home.

Don't worry bout the 4 year old being shy, he'll come round once he gets to know you, don't try too hard, kids see right through that. And you got the right idea about being a friend and adult figure not their mum, though you will have to discipline them once you've all had a bit of time together, they'll run circles round you otherwise. Be consistent and make sure your boyfriends parenting is more or less similar to what you'd do, or at least will compromise, and you both show a united front. Children can be manipulative and quite horrible really. (Not all but some)

It'll be hard not having your friends and family around for support. Being able to go to a friends place with a bottle or two of wine has been a saving grace for me several times! Hopefully he's got family around for babysitting, cos if he has his kids every weekend that takes up a lot of time and if you're not used to sharing a boyfriend with kids it may be bit of a shock.

As for the ex? All I can say is good luck. The worst thing about BMs is that they are always gonna be around whether you like it or not, and your boyfriend is always gonna have to have something to do with her because of the kids. If she hasn't accepted that your boyfriend hasn't moved on yet it could be trouble. Though with all the kids she's got in her own house maybe she won't have time to give you any grief!

Choosetosmile says it all very well actually. There are lots of step-parenting books in the library that may help as well.