@SEA2508
I think you are doing the right thing staying with your child.
However, this is one of those occasions where you just have to accept things are what they are.
The choice to be a blended family presumably gives you personally many positives,but you cannot eliminate what you may perceive as the negatives for you or your child, especially when these negatives are through choices of people outside of your immediate blended family.
Don't illude yourself or your child that blended families are exactly the same as non blended ones. Not because you can't be a happy and loving family, obviously, but because in life sometimes other people will need to draw lines, and, just as it's common to use the male/ female line, or the over/ under a certain age line, for instance primary or secondary children distinction, biological family is also a line of demarcation.
You may prefer it not to be, and you may feel that it isn't right to draw this line, but in society we need to be able to be free to categorise and prioritise.
In my own life I would prioritise biological family when there are finite resources, especially in traditional celebrations but would be inclusive of all if there weren't.
This means that had I enough money and also mental capacity to cope with a certain amount of people I would invite them all. If I didn't I would prioritise the well being of relatives over friends in a wedding celebration because of the nature of the event.
I am happy for other people to prioritise differently and was perfectly fine in not being invited to younger family members' weddings because they chose to invite more friends.