So, I have a little strawberry SMBC left and made a dozen strawberry cupcakes, but now I think I'll come up short on the icing. Can I add ps or ps and more butter to extend the amount of icing I have, or will ps ruin the SMBC (which is made without it)?

I wouldn't put PS in SMBC. Just make another batch and freeze it.

ps will make it runny. no extensions that I know if, sorry.

Thanks, guys. Kinda figured.