No - you can't.Hi,
I don't see any name in the invitation letter. And I don't remember if we were asked for the parents' names at the time of the initial application. That time iI was thinking to only sponsor my parents. Now I just realized that my wife and I are eligible for sponsoring 6 people (my parents+my wife parents+ us=6) Can I fill out forms for my in-law parents too?
If you were the one who received the invitation, then you can sponsor your parents only (not your wife's).
If your wife was the one who received the invitation, then she can sponsor her parents only (not yours).