Thanks to @wmesard for contributing this article explaining how alternate solutions / Schrödinger's puzzles work in Crosshare! If you're interested in writing an article of your own just get in touch.

Crosshare supports a number of puzzle features that the standard .puz format cannot. So even if you’re constructing offline and uploading a puzzle, you may want to add alternate solutions once the puzzle is in Crosshare. But the workflow is a little confusing the first time you do it, so here’s how…

While in the constructor scroll down to the bottom of the Edit panel, and click on Add an alternate solution. You will be redirected to an edit screen containing your grid. Then click on a square and enter its alternate answer. Repeat as necessary.

For example, if you uploaded a puzzle that had “CLINTON” as an answer, and you wanted to also accept “BOBDOLE” (like the famous NYT puzzle from Election Day 1996), you would click on the “C”, and type “B”, then move to the “L” and type “O”, and so on. When you’re done, click Add alternate.

Note that the alternate answer forms a set. In the example above, the solver must enter either “BOBDOLE” or “CLINTON”. They can’t enter “BLINTLE”. If you do want them to be independent, create multiple alternate solutions, that is, multiple sets. For example, if your puzzle contained “MOM”, and you went through the “Add an alternate solution / edit / Add alternate process three times”, replacing one letter of “MOM” each time with letters from “DAD”, then the solver would be able to enter any of “MOM”, “MOD”, “MAM”, “MAD”, “DOM”, “DOD”, “DAM”, “DAD”.

Alternate answers can also be rebuses! Select “Enter rebus” from the menu, or press the hotkey as you normally would when entering a rebus in the grid. One thing to be aware of: when you’re done entering an alternate rebus, be sure to select another square before clicking Add alternate (so the blinking cursor goes away). Otherwise your edit will be lost. [Mike said he’s going to try to fix this, so by the time you read this, it may be a non-issue.]