I assume in your question that the support you are referring to is the covert contact between GBC and TM? I think this could perhaps also be construed as them supporting GBC as opposed to supporting TM.
At this stage we do not know the date that this supporting of covert contact happened, but given the context of the report, I think it would seem reasonable to assume that it happened sometime between when ABC was reported missing and the arrest of GBC.
There was a post in an early thread where the poster said that they had overheard GBC talking to 'a local politician' at the Brookfield show the night before MSM published details of the affair, saying how humiliated he was to have had to tell his parents about it before it was published (or something along those lines - I am going from memory).
I don't know the poster who made that post, but I do know the person they referred to as 'a local politician' very well - and was told the same thing by that person. Hence my reason for thinking that GBC's family was unaware of the affair prior to the Brookfield Show.
My point is not to change opinion of the BC family - simply to allow more accurate sleuthing.

All IMO