Kids want and need boundaries.  I suggest that you discuss with your partner - what behaviours are and aren't acceptable in your home.  My other bit of advice is that when you enforce consequences for bad behaviour, you need to be consistent. If my bios misbehaved, I would tell them once what the consequences would be if they did it again, and then there would be no further warnings - consequences would always follow.  

Never reward bad behaviour.  It is easy to do this by default sometimes.  eg only giving a kid attention when it plays up - with the result that if that is the only time when he/she gets attention - it will happen more.  

Watch  The Nanny on youtube or sometimes you can find her on Bravo. Then start  watching while your boyfriend is around, "HEY COME look at this... She is amazing" lets try it. . 

Family Rule chart on large carboard poster board. Post where everyone can read it.  Start with  approx 5 NON- Negoatable rules of the home. Review during "family meeting" time.

Examples could be very similar to class room rules at school 

1. No running in house

2. NO jumping on furniture

3. Always put your toys away when your done playing (or 7pm)

4. Always sit in your chair for meals....(fyi some parents let their kids walk around UP and down, UP and down walking around during meals which is a very VERY bad habit. I noticed this parenting syle in the early 2000's now all their kids were on adhd meds because they can sit in school)

5. No hitting anyone.

6. Say please and thank you. 

*Most of these rules will also apply at school. IF on the off chance child says "YOU HAVE TOO MANY RULES MY MOM doesnt make me"....bring up school or day care. There are rules at school right?

Take this time to get to know your boyfriend before you move in... Is he marriage material? Would you want to have a family with him? IF he doesnt parent his child he wont parent yours 'together child" either.

GoodLuck