Help with candles!

Well you have to secure them in one way another - If they are pvc, maybe fill them a bit with great stuff and stick a plastic stake (like from tents) and stick the stake in there before it dries. Now you can dig them in the ground or styro of the tombstone or prop. Just my 2 cents of ideas.....

Are they made such that weight could be added to them, rocks, or such inside the pvc? Might help

If your ground is hard as cement come end of October, maybe you can affix the bottom of the PVC candles in an upright position to a flat board that would act as a base that can add some stability from the wind blowing them over. The board can be painted or covered to blend in better with the surrounding area (table, ledge, ground). Add faux grass, rocks, faux fall leaves for camoflauge for a ground base.

We have the same problem where we are at. For my PVC pipe candles I actually put a little bit of Quickcrete in the bottom so that they are heavy on the bottom of the candle and since in the Northwest we get a lot of rain I also dig it into the ground a little. Also know that if they blow over and look like they have blown out or have been forgotten on the ground by a tombstone that will add a little authenticity to the graveyard. As for other small props it depends on what it is on how to best affix it to the ground.