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A previous question "Can Conjure Animals beasts be used as mounts?" suggests that a Druid could use a summoned animal as a mount. However, how might this work in combat? Would the conjured animal act and be controlled like any other mount?
Furthermore, could a conjured animal act as a mount for another party member? Per the spell (emphasis mine):
The summoned creatures are friendly to you and your companions. Roll initiative for the summoned creatures as a group, which has its own turns. They obey any verbal commands that you issue to them (no action required by you). If you don't issue any commands to them, they defend themselves from hostile creatures, but otherwise take no actions.
Could the summoned animal be controlled as a mount by the other party member? What if the druid commanded the conjured animal to obey the commands of the other party member, or ask as a mount? Do summoned fey spirits act like the animals form they take?