Explain your idea. What do you have to do to build the relationship?
As an example ...
Page 1 of NPC - no conditions. NPC asks you to go get something for them. Turn on self switch A.
Page 2 of NPC - conditioned by self switch A. NPC asks if you have the item. If you have it, you give it to them (by removing the item from inventory). Variable = 1. NPC asks you to deliver something to someone else.
Page 3 of NPC - conditioned by variable >= 1. NPC asks if you've delivered it. If you have (turn on a switch on the event/NPC you deliver it to, then check here if the switch is on), Variable = 2.
And so on.
On the final page that has +1, have them join your party, then turn on one more self switch, and add a new page conditioned by that self switch with no image and no commands.
You do not need to use a plugin for this. You can put the tasks in your quest journal, but only for the purpose of logging them. Don't try and use the quest journal to make events behave differently. It's overcomplicating it.