Another wedding problem

We have a very difficult relationship with DIL which means we have hardly any contact with grandchildren & limited contact with son (although we still get on well with him).
Next year, DD is getting married & is adamant that DIL should not be invited. In reality it is quite likely that DIL will decide not to come but if she is not invited I know she will use this as another reason why we can`t see the grandchildren & will make it more difficult for our son to see us.
When I try to persuade DD to change her mind she becomes very distressed - she hates DIL for everything she has done to our family & does not want to have to face her at the wedding.
Since everything blew up between us & DIL (for no reason) I am very nervous of any sort of conflict with family members & don`t want to upset DD. I have promised that if DIL does come I will keep her away for DD & make sure there are plenty of photos she isn`t on. (Bizarrely - when we do see her she behaves as if everything is fine between us so she isn`t likely to play up on the day.)
Our main hope now is either that DIL will tell DS that she definitely won`t come so we don`t have to invite her - or that DS & DIL will have separated by then (which is possible)