Seniority on absorption

I m appointed as Clerk in a University in August 2014 and still working as Clerk. In my University a clerk came on deputation in June 2015 who has joined in his parent University in 2009. Now he has been absorbed in my University in the month of Dec. 2014. Now plz tell me where his senority will be fixed ....above me or below me

December 2018

will depend on the conditions mentioned (and majorly on, accepted by candidate if any) during absorption
department free to consider seniority as mentioned in both types
it is mostly depending on need of absorption,means whether it is done in public interest or on own interest