Boomerang,
Land in the south does not change ownenrship no matter how long the owner is away from Cyprus.
Regaining possession is governed by residence. Those that left CYprus before 1974, or who remained in the south, or have returned and reside in the RoC for six continuous months regains possession of their property. There were two cases in which GC refugees from the north were eviced from property when the original TC owner returned and fulfilled the residence requirements.
In the north ownership and possession of land by GCs were abolished initially by an article in the "constitution". WHen Europe told them that this would not fly they set up the properties commission which manages to hear five times as many cases on compensation compared to cases for repossession of land.