Maltipoo protective over 1 child...

So I have 3 daughters, Iam married, and before a week ago, currently didn't have any dogs.
I was on my way to drop my daughters off before work & stopped to get gas. There was a tiny Poodle ( turns out to be a Maltipoo) roaming the parking lot trying to get in any car door that was open.
Being the person I am, I brought the dog & kids to the sitter, posted him on sites, and had him scanned after work.
The first day I could tell he and my middle daughter, 7 yr old, had a bond. By the 2nd day, the Maltipoo had made it clear my daughter was his.
Me, my husband, or other 2 girls can not touch her or get too close without the Maltipoo snapping or growing.
Is there a way to stop this without breaking their bond?
And I also Remind the girls it's only been 1 week, the owner may still come.

Any experience??

 

Personally, I had no experience like this where the dog is claiming one person for his own. My dog likes everyone, but prefer my youngest son. He will go with anyone that calls him over.

A while ago, I saw an episode on Ceasar's TV series when he addressed this problem. You can look up on YouTube or your TV channels. There were some good tips in there.