DSis isn't speaking to me.
In a nutshell, she makes plans (with me and/or DM) then if her DH doesn't want to come or they change their plans they always put us last and we have to fit round them or they just cancel altogether.
It came to a head when she said they would come for DD's 4th birthday. We were all going to stay the night before at DM's and spend her birthday there. Except for whatever reason they changed their plans and only let me know around 7pm on that evening they weren't coming and I had to tell DM. DM and stepdad had had renovations done recently so had worked really hard to get the house ready for us all to stay. The other room was set up for them so then DD was getting excited for someone else coming. So I was pretty annoyed and got in touch to say I was fed up of her always cancelling and said it wasn't fair on DM and SD who had put so much work in.
I'm fairly sure it's always her DH who changes his mind because it's usually her who sets up the plan in the first place. Fine if she doesn't want to see me/DM but it's always her setting it up so why do that if she doesn't want to come?
So we are all supposed to be going to DM's for Xmas, but she isn't talking to me - I don't know if she will be different in person. I don't know whether we should go to DP's parents instead now.
This is all so petty isn't it? I think we bring out the worst in each other. What do you think I should do?