The invitations from Ancestry are notorius for not being received. If we could have a copy sent to our own email address, for one thing we'd know they got sent, and for another we could forward it to the person we wanted it sent to if they don't get the one from Ancestry, and they will get the one forwarded from us because the email will come from our own email address, which is likely already in their 'safe' list or address book, unlike Ancestry's invitation address, which is likely to be treated as spam by the email program or client.

I really don't see what's so hard to understand and it seem to me you're being obtuse on purpose.