Yourself vs Yourselves

Which of the following is correct-

• Keep those smiles to yourself

or

• Keep those smiles to yourselves

When referring to more than one person

Solution 1:

If you're referring to the smiles of more than one person, then you are addressing more than one person.

In the event of a foreseeable danger to multiple persons, you would say

brace yourselves for impact...
prepare yourselves for freezing temperatures...
you will be exposing yourselves to high heat...

Similarly, keep those smiles to yourselves is something exasperated teachers might say to their students.

Solution 2:

Yourselves would be the appropriate choice here since smiles is plural. If you were to refer to a single person's smile, you would then use yourself.