I have a baby girl who is 3 weeks old.I don't really consider myself over protective and have let pretty much anyone who asks (that I know well) hold my baby but I am becoming increasingly uncomfortable with my mother in law and my boyfriends brothers and sisters seeing my baby.As soon as we arrive at their house the baby is taken from me or the pram and is not given back until we leave.the children are 4-7 and get in the babies face constantly,kissing her and just standing far too close,both me and my boyfriend have tried telling them to back away a little but my mother in law just says that their young and basically to get over it.I don't want my baby to get ill and no one else seems to share my concerns.I think the issue is made worse because we have to see them all the time.If we don't see them for one day we get texts and phone calls saying that they miss the baby and that we need to go over there.Its now starting to become a problem between me and my boyfriend because I'm constantly trying to get out of seeing them everyday and so he's offered to take her there himself while I stay home but I'm too uncomfortable because I won't be able to control what's happening when I'm not there.I haven't told my boyfriend how I'm feeling because I don't know how to say it without him feeling that I'm attacking his family because I'm fine with my own family handling her (no children). Rant over. Any advice?

If you are fine with YOUR family doing it just not HIS family... then he would have a legitimate reason to get upset, because your family can make the baby sick just as easily as his can.

A mother has a lot of RIGHTS. You are still weak and tired (say so even if you aren't). You want your baby to have peace and quiet most of the time, with YOU. Alone. With good milk production. Blah blah.
Newborns have a lot of immunity until they are about 3 months. But no need to mention that.
Tell your boyfriend that if he wants to run the show to give birth to another baby himself.
No, really, sit him down and tell him that being a couple is COMPROMISE and negotiation and communication and understanding. I think you should compromise a wee bit for his sake, but he should back off a lot more for both you and the baby's sake.
Draw a baby face on certain days on the calendar that are allowed out for visits.
2 days a week max? You decide.
Tell him it can be re-negotiated on April 1. And so on.