Leveling and getting skill points with only 2/3 party members present? Can the absent players "catch up"?

I'm the host of a server and I play with two friends. I have no life so I'm often available when either friend A or B asks to play, but we rarely get to play as the whole group. The issue is that when friend A is playing with me, friend B gets left behind and vice versa. I'm lvl 9, friend A is lvl 7 and friend B is lvl 5.

It's already very noticable that I'm higher level than these two, but I'm also the one that's always present when we take out shroud roots and finishing quests.

So.. is there a way for friend B (especially) to catch up and gain the same skill points we have? For example, shroud roots give skill points as a first time bonus and after they respawn, they give me nothing. But if player B wasn't present when I took out the shroud root, can they still get their own first time bonus after taking out the same shroud root by themselves or is the skill point lost forever?

I love the server based progression but it definitely has its downsides when people's schedules don't match. How do you handle it?