you want to avoid the double ee sound I guess so 'i', 'ie', 'eigh' and 'y'
maybe try 'a' names like:
Maya Holly
Starla Holly
Linda Holly
Sophia Holly
Eva Holly
Cassandra Holly
Jessica Holly
Lola Holly
or names that end in a consonant:
Rachel Holly
Eden Holly
Juliet Holly
Vivian Holly
Avril Holly
Amber Holly
?lyn Holly (add anything befor lyn)
Beatrix Holly
Elinor Holly
Isobel Holly
Jean Holly
Helen Holly
Iris Holly
Violet Holly
Scarlet Holly