Hi
Yes, since you have both you will need to add addition switch or create a MST for the reader program. If the reader isnt needed on those and they want to user the reader in phantom you could uninstall the app from their device. This is very similar to having Acrobat and the Adobe reader installed on the same device.
https://kb.foxitsoftware.com/hc/en-us/articles/4403064938516-How-to-set-Foxit-PDF-Editor-as-the-Default-PDF-Viewer-Without-UAC-Prompt-
Yes, since you have both you will need to add addition switch or create a MST for the reader program. If the reader isnt needed on those and they want to user the reader in phantom you could uninstall the app from their device. This is very similar to having Acrobat and the Adobe reader installed on the same device.
https://kb.foxitsoftware.com/hc/en-us/articles/4403064938516-How-to-set-Foxit-PDF-Editor-as-the-Default-PDF-Viewer-Without-UAC-Prompt-