Yummy I posted as below on another thread (...I hope that my description of how I dealt with my MIL and created a tolerable relationship might help a little bit for you in working out your own approaches ......I also suffered comments about another baby and weight etc ...I just refused to rise to the bait, just said that my husband and I would decide together about another baby; on weight I asked "What d you suggest I do about it?" ...listened, smiled, nodded etc etc and did as I saw fit. When she said it again, I said "Oh yes, you have told me your ideas, thanks for that!"...)
My MIL was a somewhat difficult and demanding personality with a tendency to find any way she could to ensure attention was always on her. However she was my husbands mother, adored by my FIL (who was very different!) and I worked incredibly hard to develop a relationship with her over time. It took a lot of slog, some tolerance of foibles and a refusal to allow unpleasant barbs etc to get to me or cause problems. The one area where I would not compromise was in relation to our children but I was careful to deal with any issues directly but kindly, always finding a way to acknowledge her role as a Grandmother , whilst making it clear if something was inappropriate. I used "broken record" if she ignored me the first time, just repeating what was not acceptable endlessly but gently and kindly and always repeating her important role as a Granny etc etc. All this did work and we developed a tolerable relationship. I would take small gifts and flowers when we visited and laugh when I got them back wrapped up for my next birthday!! I listened for things she liked and made sure those were bought for her birthday or Christmas. So, I was no walk over (far from it) but I was determined not to allow her to cause problems between me and my husband; he did stand with me over the children which helped. He knew that I would always stand up for myself in my own way and I never expected him to speak to his mother on my behalf.
I am not suggesting this was easy nor that I was perfect in handling it (far from it!) ...but it certainly makes me think when reading some threads on here ...and also in relation to the work I do to try and develop/maintain a relationship with my own DIL - almost reverse history repeating itself I think! And yes I am aware that I am the common factor in both relationships before anyone points that out to me and maybe suggests that I should consider that! I have...endlessly!