One of Each Mini for Devotion?

If I have four Miniature Hydras can I add them all to the Monument of Devotion or can I only add one to count?

Only the first of any kind of mini will count per account. This would mean that you can only dedicate 1 hydra and 1 necrid horseman (as an example) for one count to the HoM each. Adding a second hydra to another character's HoM (you can't add the same mini to the same character's HoM twice) would not have any effect on the count.