Looking at jisho, it seems that 愛しい can either be pronounced いとしい or うつくしい or かなしい. Am I right in assuming that when it is pronounced うつくしい, it has the same meaning as 美しい(beautiful), and when it is pronounced いとしい, it has the same meaning as 愛しい (beloved), and when pronounced as かなしい, it means 悲しい(sad). For cases when it is pronounced as かなしい and うつくしい, what's the difference in directly using the kanji 美しい and 悲しい against using the kanji 愛しい？
Addendum: The word 愛しい seems to have drastic difference in meanings. From beloved, to sad, to beautiful! I am assuming it's main meaning is really beloved rather than the other 2?