Plus one's names ...

Might seem a rude question but why are you paying for people you don't know the names of to be at your wedding? I'd just invite work friends as a group not even with partners never mind their children!

I agree with @Km86 that if you don't know these people well enough to know their partners' and kids' names, then you might want to stop and think about whether you really want them to have space at your wedding. I've usually known the names of colleagues' kids and partners long before I've got to the stage of wanting to socialise with them outside work.

If you really do want them there, then the best way of finding out their names is simply to ask your co-workers. You can either work it casually into conversation or just ask them direct , explaining that you want to put the name on the invite.

My H2B knows them more then I do and has socialised in the past with them but his memory is that wonderful, its not helpful. I dont want to exclude children, I know it can be hard to find childcare and I want people to be relaxed and not stressful. If people dont want to bring their kids then I wont be upset. My guest list is small that kids aren't a bother. I want people to enjoy their time and not have to rush back for their partner or kids.