Sidechain with FxSend/Return possible?

Hi,

Is there a way to sidechain using external signal coming from FxSend/Return?

For example, I’m trying to Sidechain compression a Vocal Reverb Group using the Vocal signal (multiple singers). I know that I send all Vocals to another Group, and then use that for sidechain to the Vocal Reverb Group. However, I’m trying to save that Group for another purpose and see if there is a way to utilize the FxSend/Return, since I already have all of my vocals sent to that.

Thank you in advance!