Ok I will try and answer what I believe is he question your asking. I hope this won't cross the line of the rules but I can't see it as such.
The difference or line [as you will] between keeping things consentual and maybe 'groming' [for lack of a better word] is that you always give control of the situation to your younger friend. That means if she says 'NO' or 'STOP' that is just what you do to keep the relaionship as consentual. How is that done? If she likes to cuddle that is fine but if she doesn't want you to pick her up to cuddle or sit in your lap then you respect her feelings in that regard. If the next day she does ask you to maybe pick her up let her sit on your lap then you are allowing her the control of going where she wants to go in the relationship. If she doesn't ask then you don't go there as she has already established that 'line'. Also if she wants to sit in your lap one day but isn't willing to the next day then you allow her that and don't push the issue. You let her control what happens and you won't be crossing the line of groming.

Hopefully that helps with the question you asked.

THE Wolf