The first place to go is the WCC records for Cemetery burials.  You can search these details via their cemetery search website via the below link:    

https://wellington.govt.nz/services/community-and-culture/cemeteries/search-cemetery-records  

Here you will find out whether your relative was buried or cremated and if buried the specific location of the plot.

The WCC are developing a new way to find plots via GPS tracking.  For the present we are aware that finding plots can be somewhat challenging, especially old ones.  The Friends are more than happy to help you find plots.   We can provide detailed instructions and maps to support this. Please contact us via our Facebook page and we will make contact with you.   On our open days, we will have people available who can take you into the cemetery and assist with finding plots.