I think have to do what feels right for you. I certainly don't think BF should be hidden away, but I also think you should be relaxed as possible when doing it, whihc you won't be if you feel self conscious. I also think it would be a real shame to limit / ban visitors in the first few weeks, as some have suggested - showing DD off was my favourite bit!!
From personal experience, I found BF quite hard, as DD would thrash about a lot, have difficulty latching on, suddenly pull away leaving me sputing milk everywere etc! It got easier after first few weeks, then harder again at 3-4 months, when she seemed morre distracted and needed a quiet space to do it - that was when I stopped!
I did feed out and about / in front of people, with aid of a scarf, but didn't like doing it because it was hard to be subtle with issues above, and for some reason felt particularly uncomfortalbe in front of my FIL (and to a lesser extent MIL) and my own dad (same as Chunky Pickle said really) - not because of their reaction, but just me. So I wasn't afraid to leave the room if that was the case (although as some have said you do miss out on a lot that way, but also a nice chance for peace and quiet / to sit on the bed reading a book!) No one seemed to mind that, although I did try and get people who I wouldn't want to feed in front of to visit when DH was there to socialise with them where possible. I guess having the older child there will help with that in your case. once she started getting distracted, I even found myself sitting in the car when out and about a couple of times.
In reality it didn't arise with in laws much, as sadly FIL was being diagnosed with terminal cancer when DD was a month or two old, and they don't live near by, so we didn't get to spend as much time with them as we would have liked in the early days, and then I stopped BF (partly because it was difficult and partly due to retunr to work) at 4 months anyway. Maybe I'd have got more used to it if had to do it more (and got sick of leaving room!)
One friend said her tactic with visitors was to ask them to go to the kitchen and make a cuppa whilst she got latched on, then she was happy for them to come back in once got going!