And close the old holes. Almost always would be part of a tear out.

You have to gut all of this and open up the walls and maybe the floor to change any of it. Plan and diagram this all in advance so that it passes inspection.

Yes, it's possible, but not necessarily easy. How the lines currently are run and where you want them to be relocated to is the main issue. Typically a deck/floor mount runs through the floor, so how you will extend through the floor and up into the wall is the challenge you will face. It will determine how much demolition will need to be done and what will need to be repaired afterwards. If you're planning a major remodel at the same time, that's one thing; but if your only objective is to move the plumbing from one location to another without any demo work or repair of surfaces afterwards, that's something else entirely. Only a contractor and/or plumber onsite at your home can help you figure this out.

Many thanks to each of you. Clearly you are way ahead of me on plumbing stuff, because I didn’t even know enough to explain the question correctly, so let me amend: The floor tub filler has NEVER BEEN INSTALLED. I moved house unexpectedly, and am only trying to replace the existing fixtures in my new house with my STILL IN THE BOX very expensive Herbeau floor/deck mount tub filler, no moving of plumbing lines, I think, although I suspect I would need to repair some tile after removing the old spout and knobs. Basically, I’m asking if the deck mount set can be altered to go on the wall, into the existing plumbing lines. Again, I so appreciate your help!

Post some pics. But a vertical filler can’t be made to work horizontally.

So it sounds like you have an existing wall mount tub filler that you want to replace with your unused deck mount...correct? Totally apart from the issue of trying to figure out whether your new fixture can even work as a wall-mount, there’s the issue of what the existing plumbing is inside the wall. You may well have fixed spacing of the hot and cold supplies that won’t be compatible with your new one without tearing into the wall and doing re-plumbing. You need to: 1) post pictures of the existing plumbing you want to replace and the new plumbing, and 2) contact Herbeau directly to see if this can be made to work in a horizontal position. This will be much more complicated than you probably thought. One of the reasons is that a floor mount typically has a metal mounting plate that needs to be screwed into a solid surface, and it’s not clear what surface you have on the wall that would support the hardware.

sounds like, unless Herbeau makes some sort of adapter, I’m stuck with $5,000-worth of tub filler and pipes that I can’t use. Bummer. Thanks for your advice!

It might be possible to open the wall and attach a solid piece of wood between the studs that would provide backing to screw a mounting plate into. But what do you have now in that wall area...tile on sheetrock, or what? Again, a picture would help.

I don’t have a picture of the filler because it’s packed. I’ve been trying to copy/paste an internet picture of Herbeau Monarque deck-Mount tub filler, but can’t seem to transfer from other sites to this. As to the existing bath, it’s a 1920s bathroom with ceramic tile tub surround, into which a faucet with separate handles are mounted.

Ok. Even without a picture of the wall, I think it's safe to say that you would have to take out a couple of square feet of the wall to get access. You would need to get into the wall to remove the mixing valve which the faucets are attached to, change the spacing of the hot and cold water supply lines to conform to what the new hardware required, attach some type of wood backing to the 2 X 4's in the wall to support the new bracket, and then close up the wall and repair it. It might be possible to do that all from the other side of the wall if you had access, but it would be a challenging job. If you are dealing with a plaster wall, it increases the difficulty.

I should also note that you originally said "deck-mount or floor-mount" and those two things can have very different requirements. I just found a picture of the Herbeau Monarque 3630 Tub Filler. Is this what you have?: Tub Filler

If so, mounting it on the wall would have the spout pointing toward the wall, rather than downward into the tub; and the hand shower would fall out of the bracket. If you have something like that, the only solution is to construct a deck on the wall to have the fixture oriented properly.