hi Ron,
the EIP tab has a place for a conditional - just set the expression here to allow or prevent EIP on that cel..
changing a cell from string to drop though is a little tricky, and would require some embed code. I recommend generating the code for a string, having a look at it, then copying it to the clipboard. Then generate for a drop, and inject the string code as an embed, using a condition around the string & drop.
Cheers
Bruce