Just as an aside if you ever get sticking caliper pistons always carefully remove the main seal because in the seal groove you might find corrosion that strangles the seal and thus makes it stick again. Remember which way round the seal went with a fag packet sketch and use the cap clip from a cheap BIC brand pen as a lever to prevent damage.
I lost all my brake fluid on my 156 as a result of waiting for parts it seeped out and proved to be a right mare to bleed, in fact i had to use fiatecuscan to shuttle the abs valves while bleeding the system which is akin to rubbing your belly and patting your head
(when i say "I used fiatecuscan" it was a teenager who has transferable gaming skills)
Those systems can be stubborn to bleed and its also important to prime the master cylinder from dry by cracking the banjo bolts until the fluid flows a bit with a rag underneath to catch the spills.