If you look at my floor plan, you can see a dotted line that runs horizontally. We're pouring the floor in two parts- the first pour below the line, and then later above the line. However, the manifold is in the lower half. Just behind the toilet.  The distance from one slab to the other is only a couple of feet.

So how do you pour one part of the slab and still be able to have PEX from the later pour be able to have a path to the manifold in the other part of the slab that was already poured?

There's got to be a way. But I'm sure not seeing it. Some kind of special raceway from one slab to the other?

I would do a second manifold for the second pour. then you only have its feed lines to be concerned with, and they could be surface mounted on the wall, run through the ceiling, or you could sink the feeds now and just protect them where they emerge from the first pour.

Thanks for that idea.

I'm working with the concrete contractor to see if we can manage another alternative.

Interesting situation.