[Jeremy]

Yeah, I don't think we ever did that for UR, but it's something we do regularly for Fanuc, we call that a "Dripfeed".

If you go to "Tools"->"Options"->"Program" you should see an option "Maximum number of lines per program".
Try activating that and see if the program is indeed split into pieces. If it's not the case, we can add that feature to the post-processor. I can't remember if it's done or not for the UR.
This will generate a "Main" with program calls to all the pieces of the program.

We then create a Python script using the FTP transfer feature of the robot (UR as it, so that's great) and we push the Main and the first 2 pieces.
We then monitor when the first piece is done (therefore the controller starts executing the second one), we delete it, and we push the third piece. And so on and so forth.

You can take a look at the FANUC RJ3 Dripfeed post-processor with a large program (you can use your UR station and just select this post, no need to create a station with a Fanuc robot) to see what it looks like.

Jeremy