Link two projects in Project online using REST API

Hi the linking between tasks in two or more schedules, is a manual exercise where you'd open and check out both projects, create a 'simulated master' schedule, create the linkages between the schedules, the NOT save the master but publish the projects with the cross project links established. Due to the nature of this tasks I do not believe you'd even want to do this programmatically, as the process of establishing the tasks, how they're ordered, etc. requires some planning and thought. As far as I'm aware this activity needs to happen in the MS Project Pro full desktop scheduling client, so any automation would require literally having a program open the Pro client, understand some logic to make the connections, then do a publish activity of each schedule.  The pure time and cost to automate this (if it's even possible) would greatly outweigh the time it would take to do the linking exercise listed above, plus the ability to check the linkages are done accurately, with the right pred/successor relationships. ordering, etc. is just a task that would be overwhelming to automate.....

FYI we've done alot of automations using this type of 'instantiate MS Project Pro to do xxx and yyy' and it's very complex, and honestly tough to support due to its custom nature.  This may just be a case where manual processes work best.