sister-in-law and children are favourites

[Onlyme100]

So I have an older SIL (DH's side married to DH's older brother). MIL seems very close to this older SIL, she seems to be at MIL's all the time as do her kids, they eat there, go out etc. I'm an outsider to the family so somehow feel a bit left out and am always conscious of how my kids are treated to. As for my sil - she never did like me as she wanted her DS to marry my husband ( awful I know). Anyone else have an stories to share - just so I don't feel alone in this matter?

You haven't really provided much information? Surely your family is also involved in your MIL's life? And honestly it doesn't sound as if they are excluding you, is it really your business? I don't really understand your comment about your SIL wanting the marriage, if she is your husbands sister then surely that is near illegal, and if she is your brother's wife then there must be a large age gap (if she encouraged it), so maybe that explains why she is closer to your MIL?

Well, she is my husband's brother's wife. His actual two sisters are quite nice. But she is a far relative from my mil's side of the family, so from the same town overall iykwim.
So here are a few examples of why I do feel a bit left out:
1 - Children's birthdays are celebrated for sil's children at mil's house.
2- SIL is always putting me down in front of MIL. Talking behind my back too (I know this due to other member's telling me) quite hurtful.
3- SIL basically lives at MIL's house 24/7. Even though she has her own house.
4 - They shop together, eat together etc.
Perhaps they it doesn't sound like they are excluding me, but sometimes it does feel like it. I guess I wouldn't even care so much if my SIL was more acceptable of me going out of her way to make snide comments about me.

Hmmm... I don't think you can really do anything about the birthdays, is your SIL less financially stable than you? Or has she always been the one your MIL sort of doted on iyswim? The snide comments are a different matter. Obviously the right thing to do would be to be the bigger person, but that gives her the satisfaction. What types of put downs are they? As in passive aggressive or full blown, and how does your MIL deal with this?