There's so very little to base this on, but I'm going to throw this out there: the guy Jill is talking with to help start a campaign in Lana's honor, Jonathan? That's Lana's old boyfriend.
On their way to meet Jill's parents, Jill mentions that Lana bringing her boyfriend home was one of the things that started fights between her and Geoff. She brings it up because she's nervous about how MC will be received, and doesn't have another frame of reference.
Now we've seen Jill communicate with Jonathan twice, and learn he is associated with support groups, and can help Jill with her attempt to create a campaign.
It's not too much of a leap to believe that a reformed punk who might've contributed in some way to his girlfriend's death would want to help people process their own grief, as well as try and prevent similar tragedies. Her death is still shrouded in mystery, but there's hints of drug use, even a possible OD.
Jill doesn't seem the type of person to hold her sister's death against him, especially if he is truly remorseful and has changed for the better. They might not be close, but there's still a connection, hence not talking a lot but Jonathan being on the back of her mind.
As for why Jonathan never made his own campaign in Lana's honor, it wouldn't be very appropriate without the Royce family's approval, and I don't think he would get it from Geoff and Amelia. Jill mentions that "they" would try and stop her, I imagine this is why. They want nothing to do with him, and might even consider it an insult.
Again, there is so little to try and formulate a theory, but I wouldn't rule it out.