Reader Question: She and I's

A reader asked this:

I am hoping that you will be able to clarify some compound possessive sentences.

I have been hearing people say things such as:

"She and I's relationship."

or

"Sally and I's relationship."

I have also heard:

"It is the end of John and your's vacation."

or

"It is the end of you and John's vacation."

or

"It is the end of your and John's vacation."

When I hear or read any of these, I find myself feeling annoyed and frustrated. Annoyed because none of the sentences sound correct and frustrated because I do not know the proper usage.

I was happy to help her. Here's what I said:

These choices would be correct though not ideal:

Sally's and my relationship
John's and your vacation

Recasting the sentence to avoid these awkward possessives works best:

the relationship between Sally and me
the end of vacation time for both John and you

I hope that you's and your three-day weekend is fun! (I mean, your weekend!)