How to get sims from different lots to all go to a community lot?

You can't, sorry. But if you are making a movie with them (or so it sounds) you can move every one on to the same property and build "sets" and "props" for your movie. That way, you will have control over all the sims you are using for your movie. Hope this helps!

Well, whatever you do, you won't be able to control both families at once. Not unless you combine the families so they're all one household and then go the community lot.

You can form a group with the other family and meet them at the community lot (if you have Nightlife), or you can call Transportation, select "Invite Sim to Lot" and then you will automatically meet the other Sim there. The only downside is you can only meet one at a time. But, if you do have Nightlife, you can use a Sim's cell phone to call all the other members of the family and invite them over. After a few phone calls, everyone should be there.

One family has their own ways of doing things in their own homes, I don't think its possible to uproot a family and put them together with another family, without messing up the kids for one, and the adults as well, I think you leave families alone, allow them to live their own lives with their families, and you do the same.

You can't do that as you're explaining it. You'll have to use the phone and form a group with the other family and send them all to the lot together.

I've tryed to do that , actually move a family to another lot, but, I can't figure it out sorry!