A: Hey, kostariko!

Unfortunately, with the way the backend setup works for the SendFox Plus Exclusive... you can't "stack" or add it to the top of an existing SendFox (non-Plus). It's simply not technically possible because they're considered two different deals in the backend for a variety of technical reasons.

Hopefully, this is something we can solve in the future, but it is technically complex and we don't have an estimated timeframe on when something like this can be done. Sorry for the inconvenience there.