My daughter is IY”H making a wedding, I will be invited to Sheva Brachos after, can I as a Zeidy go the Sheva Brochos during the week after, and if yes can I sit and eat regular with the other people
MazalTov. You should have a lot of nachas from the new couple.
Regarding your question Since you are the grandparent of the chosson or kallah you you may attend the sheva brachos, the same way you attended the wedding.
Tziyunei Halacha pg. 508, Hilchos Aveilus pg. 211, 215.