I bought an asus transformer trio (2015) which i opened only after 4 years (2019), so a windows 10 upgrade was in order. After the update, partition setup was like this:

Recovery | EFI Boot | MS Reserved | OS

i wanted to recover disk space by deleting RECOVERY partition from the new ssd i had cloned it into and merge it with the OS partition, here was my solution:

-delete RECOVERY partition with mini partition tool

-image the resulting partition setup sans RECOVERY, UNALLOCATTED SPACE in lieu on a usb disk

-recover image to my ssd via macrium reflect, with method of dragging one partition at a time to destination disk in this order: EFI Boot | MS Reserve | OS

-what will remain at the left/end is the UNALLOCATTED SPACE which i was able to merge back to the OS partition with ease using mini partition tool

Hope that Helps!