Why does SIL 2 want you two to "make up"? Is it affecting the rest of the family? Is it spoiling social events?
If not, I would just say to SIL2, you are both very different people and you think it best to keep apart. The other sister must just accept this.
Is this a thing now in impoverished Britain
Setting the format for a thread - is it reasonable or unreasonable?
What do you wear at home in this hot weather?
Loving the common thread so much thought we should go “POSH”