I'm trying to ensure that companions can find their beds in companion-friendly revamps of the Vanilla buyable houses. The problem-- if it is a problem-- is that the companion beds are often in another cell of the house, accessed via a load door. The cells are well pathgridded up to the door, but I am concerned that the companions won't use the door to get to the cell with their bed if their sleep package becomes active, since the path 'stops' at the door and starts again in the new cell (but how would they know that? or would they?).

According to the Wiki, if I select a path node and click 'R', I can link the selected node to a reference, and indeed I can do this. However, there is no further information as to the effects, usefulness or indeed the correct useage of this function. But it seems like the thing to do, for example, to link the path node in front of the load door to the 'receiving' door, from which they would then proceed along the new grid to find the bed. And, for example, to link the node under the "place to stand if you want to sit in a specific chair" to the chair itself so that the NPC does in fact sit in the chair if they cross to that node in their wandering.

This all assumes, though, that the function works as some kind of automatic "jump to the linked object", which may or may not be true. Furthermore, it may be completely unnecessary, as for the most part companions are reported to usually find their beds (although I've heard that sometimes, in some houses, you have to lead a companion there before they will sleep in the bed designated for them), or somewhere to sit-- even though they may choose to sit somewhere completely other than the seemingly logical place.

I am wondering if anyone knows whether linking path nodes to persistent reference objects will stabilize this somewhat inconsistent behaviour, and secondarily, if, in the case of doors, whether the linkage should be to the door in front of the path node, or the door on the other side of the load.

Linking path points to objects is for the EnableLinkedPathPoints and DisableLinkedPathPoints functions. Typically this is used to create a path when a drawbridge is lowered (and the reverse). I've also tried to use it to disable grid paths when a building is erected in their way, but I've had issues with other mods essentially putting them back.

NPC's will go through load doors when their AI packages require it. Most IC NPC's have AI that takes them to other parts of the city.

As ghastley said, you don't need to use the link to reference option in this case. But if you want more of an explanation of what it does, I recently discovered this http://cs.elderscrolls.com/constwiki/index.php/Pathing_and_Playtesting in the My First Dungeon tutorial on the CS Wiki. You'll see lots of examples of the EnableLinkedPathPoints and Disable commands in the vanilla scripts - especially the ones linked to hidden doors and the switches that control them.