Thanks for all the info here.
I have created two child version of the vanilla fabricator and use the vanilla inventory so that new items get added from dev patches without the need of me having to update the mod continuously.
Everything works as it should - as in the items are added to the inventories correctly it’s just that they seem to disappear on server reboots, if you pickup and place them back down they re-appear.
I’ve added my engrams and structures in the correct places all I’m trying to do here is add my items to the vanilla fab + my two new fabs.
I think I’m just missing some kind of setting to save it on restarts - it’s just trying to find out what, I may have to do it with the graphs instead and see if it fixes it