When making a sketch relation, it is often the case that one sketch entity or the other will need to move, even if only miniscule amount. This is assuming that both entities are undefined in the axis of the movement.*

Is there a way to determine which entity is "home base" and which entity will move?

I often want one entity to stay put and the other entity to move. But I don't always want to define it first. 

My wish is that the entity I select first is the home base and the second entity will move to home. I've tested this wish and doesn't work. Once SW has in mind who's moving, it doesn't matter which entity I pick first. 

It's possible to "fix-anchor" the part as home base. But that's a bit of a hassle too, because "anchor defining" a part leads to trouble later, so I delete 95% of all anchors I ever apply. 

So it leads to a work flow like this:

select 1

select 2

add relation

"oh dang it move the wrong one."

CTRL-Z

select 1

anchor

select 2

add relation

select 1

click anchor 

delete

That turns a 3 point workflow into 11. 

* If one of the entities is fully defined, or defined enough, then it's not going to move. It automatically becomes "home base". If both entities are fully defined, or defined enough (FDODE), then the sketch relation will over define the sketch.