General :: Saving Files To Network Shares?

I have a need to roll out tablets to some of my people who work in the field, here is the problem I am running into.

I need them to be able to connect to a network share, open a document, and then save the changes back to the network share.

I am able to access network shares easily enough once I am vpn in. using ES, Astro, x-plore. Simple enough, create shortcuts to shared folder on my network here at HQ.

Problem is that if I open a document on my tablet, change something, and then save it, the changes just get saved to the temporary save location on the android device.They dont end up back on the network share.

I would like for users to be able to just hit save and have the changed document overwrite the original, same as if it was done from a windows laptop.