Interested to see what you find w/ compressed air and/or splitting them. Make sure ya use a soft material (wood) between the pistons and that its wide enough that the pistons on one side can't come all the way out if the other side remains stuck.
- forcing brake fluid into the system from either end is fine; they make bleeder kits which are designed to push fluid thru the reservoir (typically in automotive applications). The benefit of pushing it thru the caliper's bleeder is that it pushes air up...the direction the air naturally wants to go. However, I did mistakenly say to zip-tie the lever when forcing fluid from the caliper. You do not
want to do that because you wouldn't be able to push the fluid past the M/C piston. Nothing bad will happen...just won't be able to get brake fluid into the system due to the pressure.