After an extensive edit, this is probably a long comment rather than answer.
Bell's design was developed independently from Gray's, and probably from Meucci's. This article of The Guardian uses the verb "steal", but quoting @sempaiscuba, TG is no stranger to controversy.
Many "respectable" articles claim that he conducted experiments in the same laboratory where Meucci's materials "had been stored by Western Union", but in fact he had sent descriptions and drawings to Edward Grant of the American District Telegraph Company in New York.
Undoubtedly, Meucci is a father of the telehone and this was implied in House Resolution 269 by the US House of Representatives in 2002, though not explicitly stated. In its words, if Meucci had been able to pay the $10 fee to maintain the caveat after 1874, no patent could have been issued to Bell. As a matter of fact, HR269 was criticised.
An early verdict stated that Meucci's design was mechanical and not electrical. But according to Giovanni Schiavo, an Italian-American historian, this verdict is one of the most blatant judiciary mistakes in the annals of American justice. (After all, the device was called telettrofono, "telectrophone"). Meucci started to think of his design after some electrotherapy experiments in 1849.
It was in 1854 that he realized the first prototype of telephone, which he would call telettrofono. He used it to communicate from his laboratory with her wife, who was bedridden.
Unfortunately he was quite poor, and couldn't afford to patent the invention. Only in 1871 he managed to have a patent caveat, i.e. a temporary patent, but he could renew it only until 1873.
I read there is doubt about this last aspect, because he patented other inventions from 1872 to 1876, costing $35 each, but I see nothing strange: who lent him the money for renewing the patent of the telettrofono stopped doing so in 1874, probably foreseeing no future advancement for Meucci, but this didn't stop other creditors from supporting other inventions of his.