According to the CT, it is them and not the family that tend the graves but even if that is so, it was in very poor taste.
The answer to the topic Should Jeremy Bamber be allowed to cause distress to relatives of the deceased? is, of course not, but he will continue to try through his constant smear campaigns against Sheila, the integrity and honesty of the relatives that got the farm and Colin Caffell, who must never be allowed to grieve quietly when he has the temerity to think Bamber is guilty of murdering his sons.
What a wretched man Bamber really is.
If Jeremy is innocent (and I'm not saying he is, but it is what HE is saying),then he is entitled, IMO, to stand up for himself, whoever might be upset by it.
As for Colin (for whom I , personally, have a lot of respect), he did decide, of his own free will, to help in the making of the recent TV series, and to give an interview on TV. Jeremy didn't make him do that.