Ok, let's make a few things clear.
If it is about ONLY making the pattern overlap, then it is of course possible - you need to manually create the tile (copy a few to the right-left and up-down), then define the pattern's bounding box.
And "overlapping" will be absolutely possible. You just need to find the actual "tile" that repeats, and I think this is the artist(ic) part that you should take care of (at least).
If its about having RANDOMIZATION per pattern geometry island, then it is another talk, and can be an actual feature request.
More specifically - Mutimap should have "Pattern" mode, or "Pattern" for "Mesh element" mode, or the same setting in PatternModifier. Or simply make "Mesh element" mode work based on generated pattern islands (check for non-zero welding maybe?). I will report this surely.
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