You must have a bigger bathroom than mine. My 6 fixture light even with the smallest bulbs in it is brighter than I'd like.

There's nothing electrically difficult with doing this. Depending on the positioning of the existing wiring it might entail cutting into the wall a bit to extend the wiring.

we have a 10 light plain bar now. in enclosed space of about 78" wide.

so cut out drywall, drill thru studs to run wiring and new boxes? make current box a junction and split off 2 more from there to each side?

As long as all connections are done in an approved, accessable box, yeah that's about it.

So the box would have a cover that would be visible?

Are there any other options where the center box wouldn't be visible?

Thanks.

The best way to hide it would be to put it behind one of the lights.
If you're willing to do a little drywall work (or you can get to the
existing wiring trhough an attic or whatever), you could relocate
the existing wire to where one of the lights will be installed and then
pull the new one over to that.

I don't think behind a light would work or would be worth the trouble.

But in a AHA! moment, I figured I could move the junction over to one side, as it would be behind a mirror, and an exposed cover wouldn't be a problem there. i think.

You can't put it behind a mirror.
Drywall isn't all that hard.

Install "old work" round boxes where you want the lights to be. Run the existing wiring to one of those boxes instead - (the existing wire had better reach one of them!), since you're you're going to be eliminating/patching the original box. To get the wire to reach, you may have to deal with loosening a wire that's secured (stapled) in the wall to the stud. Pull addl. wire from the first box to the second box (drill stud carefully). Repair wall, install lights.

If you're dealing with older style wiring, or you feel you're in over your head, hire a professional. Consider it an investment in safety.