OK then i recommend you DL and test MiniToolPartition, for me it seems the simplist for use by "My Clients"
and if your System and Boot are not on the same HDD, that does make it rather difficult to do. but
You need to be 100% sure where the BOOT Part is, then make room for the System (OS), to move it to the Boot Part HDD.
easy to do for me, but im not sure,,,,so make a image of only the System (OS), then make a partition which is slightly larger than, boot to WinPE disk, then restore the Image (OS) the the new partition where the Boot Part is also located. make no difference what the Drive letter is, you can change it. when the image of System and Boot is on the same HDD, make sure the System is now C:
next you should be able to restart and boot normally, since the Boot Part HDD will also contain the OS part. Dism commands , BCDEdit commands, and the program which you use to make and restore the OS, should work.
I also have some clients, make a image of only C:\ (System) then do a Clean Install of so that Boot, Rec, and OS are the same location, then boot back and restore you original C: to the new C: . and I have never seen AOEMI or any other Image Program tell you that the are seperate when they are not... I have seen many time unknowly people change so that Boot and System are on seperate HDDs.
Make your image first and save on a total seperate so you do not loose anything.