How to merge two fet files together.?

[danhdv4]

How to merge two fet files together.?
I have two fet files.
One file is the morning schedule and one file is the afternoon schedule.
My school has many teachers who teach both sessions.
After completing the arrangement, I want to merge the two fet files together to print out the teacher's lesson schedule.
Please show me how to do it.
Thank

[Liviu Lalescu]

Unfortunately, it is difficult. You need to increase the IDs of the activities in the second file and also update these IDs in all the constraints in the second file.