As you know, we concatenate words with Ezafe when two words have a relation of modifier word and modified word.
But, You may not know the concatenation rule when the last character of modified word is HEH+HAMZA.
Instead, you must use HEH(U+0654)+ZWNJ(U+200C)+YE(U+06CC) or HEH(U+0654)+HAMZA ABOVE(U+0654)
You can use which you like, however, I recommend to use HEH+ZWNJ+YE because HAMZA is usually hard to see in computer screen.
By the way, Do you know the key position of characters above?
ZWNJ is Shift+B
HAMZA is shift+N