I guess I just don't want them to cut my boys out of their lives....or the baby coming....they are innocent and my.oldest boy adores his grandma and papa...
That is what you might want. But you are not actually in charge of how grandma and grandpa spend their time or choose how to behave. Grandma and grandpa are in charge of grandma and grandpa.
They may accept the child or reject the child. They behave however they do.
YOU can choose how you behave and who you allow contact with your kids and allow to form ties with your kids.
Your job is to raise your kids and shield then from nasty you are able to shield them from. Find out right now how Grandma and Grandpa plan to behave toward you all.
If grandma and grandpa choose to treat any of your poly family in less than loving/kind ways? Maybe it is best for the children to NOT hang around with grandma and grandpa.
You and your poly people are going to have to have some serious talks here about this and you watch and see how things actually unfold in your situation.
You are responsible for your own emergency preparedness. If grandma and grandpa decide to get nutty and challenge you for custody of the kids? Know the laws in your area.
I say this with a heavy, heavy heart. I'm not trying to be a wet blanket. I hope things actually work out ok after they get over the surprise of the news.
But if they don't?