Hi Emma,
Yes 573 applies even if the land was separate titles prior to the sale. If you don;t want to apportion yourself you can ask VG to apportion for you.
I would apportion the outstanding rates on the basis of the new LV’s & then write to the new owners (as suggested by Simone) & allow them to resolve the matter/s. That way they can’t say they weren’t aware when you issue the new years notices. They could have been told that the Council would issue new notices for the 2 properties because the rates hadn’t been issued prior to settlement. It’s always better to deal with the owners rather than solicitors because the owners will want it paid.
Also, Sec 560 tells you who is liable for payment & since July 7 the new owners have been liable whether jointly or severally. I would be quoting that to them as well. The fact that they didn’t get a new 603 is irrelevant to the process, once they acquire 560 says it becomes their problem.
Good luck.
JT