Start with a skirt that is full so you have plenty of room for it to move. I started with Vicky above the horse and slightly behind it. I put her on the horse at frame 20 and let the sim run until frame 60. It didn't move much after frame 30. Here is the setup

and here is the result

Here's the wind. I obviously had it set too strong. My apmlitude (what sets the strength) was 20. Also make sure your horse isn't blocking the wind. Mine is off to the side.

Another option you could try is having your figure in the location you want her in at frame 1 in the T pose and just have her move her arms and legs etc. into position for the final pose and start the horse lower than you need and raise it upto match. Sometimes moving the figure less helps draping go smoother.

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