Solve collaboration failure caused by version upgrade by resetting iPad to achieve downgrade.

Incremental GB upgrade after reset: I’m collaborating on a project with two others. We are all using iPads (me 6th gen, them 7th gen.). They just recently updated OS and GB. Since they have updated, if they open a project and save it, I can no longer open it on my Gen-6 device and am running the latest OS and GB available for that device. I’ve been exploring solutions but have come up dry. BUT…I’m thinking about this option. Will it work? What do you think or know? FYI - I am the primary producer in our collaboration.

My objective is to revert to an earlier version of GB on the two 7th Gen devices. Not a straight forward task, BUT…if we reset to two gen 7 devices, they should reset to the originally installed version, correct? If so, can I then upgrade to a version of GB between original and the latest for that device (e.g. 2.3.14)?

Thanks in advance!