1) You may have no choice put to post the 10KG from QI to blocked stock or unrestricted and then write the material off from there.
2) There is an OSS note available for reversing UD's. You might try that and then try the QAC1 adjustment. That would leave a lot qty of zero. I'm not sure the system will like that.
3) You might try reversing the reversal of the original 90 kg and put it back to the inspection lot which will give you 100Kgs again. Then do QAC1 again and adjust back to 90. Then do the reversal again which hopefully will make the lot go to 0 and status LTCA.
Craig