Help needed - Flat mount caliper on IS mount fork?

So, I'm a little confused.

I have a new, Force CX 1 flat mount caliper set on the way, in addition to a fork that will be IS-mount.

The frame is flat mount.

Is there an adapter that will fit the flat mount onto the IS fork? Visually, to me, it looks like I might be able to fit the IS->Post adapter and then the flat mount plate onto that? But I'm not sure...

Anyone know one way or another?

No, you can go flat-mount to post-mount not the other way.
The I.S. tabs sit where the flat-mount caliper should be.
DIY is probably an option but it is not going to look nice.
I have the flat-mount dimensions somewhere, I can try to find them.

Easiest thing to do is get SRAM´s matching post-mount caliper (and use an i.s.-to-post adapter on your fork)

The I.S. tabs sit where the flat-mount caliper should be.

This.

If an adaptor exists, using it will come at the expense of a huge increase in rotor size, which the fork might not be able to accommodate or be warrantied to use.

Apologies for the thread hijack, Snicks, but could you possibly tell me where you sourced your new brakeset? I've been looking everywhere for SRAM flat mount calipers but had no luck so far!