Help with MIL (long)
My in-laws live about 20 minutes away and we see them on average once every two weeks. My MIL watched DD the first week I was back at school in December and everything was fine. Lately, however, DD has been super fussy around her. She gets pretty fussy at bedtime so I know that's a factor, but today the in-laws were over during the day and she was super fussy with her. She was eating fine, had already napped, but anytime MIL held her or sometimes even looked at her she'd start crying.
It's super awkward because while MIL and I aren't super close I still feel bad. At first we made jokes but I feel bad when she finally gives DD to me and she'd stop crying. DD is 4 months old - is she old enough to have attachment issues already? We also differ on parenting styles - she would think DD was tired and try to put her down for a nap and then say to let her cry herself to sleep. The longest we'll let her cry is maybe 5 minutes and she'll usually go to sleep if she's calm, not if she's screaming her head off. The in-laws babysat a couple of weekends ago and apparently DD cried the entire time and hardly ate at all. She is in daycare and is totally fine with her.
Sooo... should I be concerned? Try to help MIL by showing her how to calm DD down, even though both DH and I have tried and she doesn't really listen? Is there a way I can make DD more comfortable around MIL? I guess I just need any advice out there 
PS - my parents are visiting for a few days and I'm worried about how DD will be, I feel bad since they're so excited to see her. Although my mom listens and totally understands that I'm DD's mom and will know how to deal with her. MIL thinks she's dealing with a mini DH... argh...
Re: Help with MIL (long)
Just offering support, no real answers. My mom lives 6 hours away while my MIL lives an hour away. My mom has come down several times, but like you, we see my MIL every other weekend. DD (almost 6 months old) is fine with MIL (we are always there too though, rather than having her babysit) but is a little more fussy with my mom (who we call "far away grandma"), probably because she isn't as familiar with her and there is more time in between when she sees her than my MIL. I noticed at Christmas that we were having my mom hold her in the evenings and that is when she is fussy, so we tried earlier in the day. My mom got a complex about it of course, which I felt so bad about. DD was better in the afternoons with my mom holding her.
About what you should do (or shouldn't do), I have found that if I try to show others what works for me to calm DD down, it doesn't work as well with them. It is more of a personal thing I guess. Also, I have found that some people who are already parents (typically the generation older than ours), take it as an insult when you try to show then how to hold/comfort/entertain, etc. DD. If you don't have a close relationship with your MIL, I wouldn't be the one to approach her. Have DH do it if you both agree that is the route you want to go. And please don't feel bad, your MIL is an adult and at this point, the comfort of your DD is more important (at least in my opinion). Just try to stay relaxed so DD can't sense the tension.
And don't worry about your parents' visit, I am sure it will be fine. One thing I have read is to not just hand DD off right away when people she isn't used to arrive, talk to them first so she can see you interacting with them and see they are your friends. This is normally for toddlers, but it can't hurt to try with your DD.
Good luck.
Is she around a lot of other people - besides you and the daycare lady?
Maybe she's not used to anyone else holding her.
My mom said that when I was a baby, I would scream bloody murder whenever anyone tried to hold me. Like, even my dad. I eventually grew out of it...
that is really rough, I don't really have any words of advice, maybe stay around your DD when MIL is holding her; how is she w/ FIL? DD cries when SMIL holds her which I know would make MIL happy if she were there to see it (I know - totally irrelevant).
maybe instead of holding her, your MIL can get on the floor w/ your DD and you and DH and you can all play
There could be many answers to this question but i'll tell you about my friend:
1. her MIL had issues calming the baby b/c she would try to sooth the baby HER way not the way the baby is used to you doing it... so my friend had to teach her what her daughter was used to.
2. At around 4-5 months her baby went through a sever attachment phase... NOTHING she did helped it... finally at about 7-8m or so she got out of it and was fine with other again...
Maggie went thru stranger anxiety (and by stranger I mean not mom, dad or DCP) around then. Then later around 8/9mo she did the separation anxiety so for us they were separate issues.
Maggie also hated my one friend Amy as an infant. She was great those first few months and Maggie saw her about once every couple of weeks. But all of a sudden she just cried whenever she saw her. Maggie was never even really alone with her much after she was a few weeks old (friend really helped out by coming over to help take care of her)., but every time she saw her, big tears and god forbid the friend tried to hold her. I felt so badly because my friend loved her and lives right down the street from my daycare. I think it may have been her glasses - they had black thick frames so it was very obvious and no one else we knew wore glasses daily. Maggie did eventually get over it around 1 year old. Sorry I have no suggestions on how to make it better except that time worked for us.