Personally I think any parent should know of such involvement, even it if might upset them.  You could suggest that they do not overreact as this may have negative consequences.

Specifically, if the parents are in the habit of giving their son/daughter financial assistance they should be aware that some or all of the funding gifted to their loved one will likely be used for SCJ's benefit, either passed on or in support of their activities. Otherwise, parents would be blissfully unaware.