Well that is a 46 gallon tank you got there and I wouldnt go crowding it up or you will have problems with fish growth. Plus your tank isnt tall enough either. I would say your pushing it a bit by adding 3 more discus in there.
Is your tank bare bottom ?? or s it planted ?? what other fish do you have in there??
For the moment I would hate to disappoint you but I would say no. Maybe I am wrong but I like giving fish space and 7 discus in a 46 gallon is a little overcrowded to me.
HTH
Jason