https://www.wowhead.com/quest=44156/another-arcandor-closes for example is given by Valewalker Farodin.
The underground temple of falanaar is part Suramar, but its own subzone in terms of quests.
How could we link this so they also show as part of Suramars quest list?

If the quest giver has a location that is in the Suramar map, then the quest should show up in Suramar as well. If you are at the quest giver and do "/grail target" do you get more than one map location? This will happen if the zone you are in logically falls into other zones like Dornogal NPCs have locations there and ones in the Isle of Dorn as well. E.g., Nagad has an NPC entry: G[219085]={'2339:52.87,71.19 2248:50.39,49.81'}. If the quest giver does not have an "outer map" location, one could be created and just added as well, though it should be close to where the entrance to the "inner map" would be.