You need a remote control with the PIP function.

It's interesting you brought this up, because I was just about to discuss
the fact that many remotes lack critical functions. For example, I've never
found a universal remote that accesses the fancy features of my Toshiba
CZ-3299K. (Indeed, none of them support the 0 button!) It appears this is
because Toshiba failed or refused to supply these codes to Sony, GE, etc.

I will be contacting Toshiba shortly.

Good luck finding the remote you need. You probably won't.