...do we also do defunct cemeteries or only current ones?
Unfortunately, there is no single correct answer for this.
"Defunct" can mean quite a few things. For instance, it could simply mean that the cemetery is no longer in active use for new burials.
On the other hand, it could also mean that the property was repurposed for reuse or redevelopment, which brings in the question of where the remains are located.
Reuse is a topic we see a lot in European countries where gravesites can have time limits on them. What happens after that depends on the local rules or customs.
For example, in Japan, where space is limited, it's common for remains to be exhumed, cremated, and then placed in a smaller urn, allowing for multiple urns to be interred in a single grave plot.
In other areas, the remains are removed, cremated, and then scattered on the grounds of the cemetery, therefore allowing for reuse of the gravesite.
I am not sure which one we are dealing with (or if we can even find out), but that would play a large factor in how this might be handled.