reactjs - react flux subscription callback , many to many relationships -

i new react , flux. trying build subscription system. many many relation ship confused on how implement callback:

the scenario:

user a, b, c subscribe item 1.

user a, b, d subscribe item 2.

user b, c, d subscribe item 3.

the items infinite, , users infinite.

so in case, if there attribute in item 1 changed, want emit change subscriber a,b,c.

due fact items infinite, can't manually create number of callbacks.

i imagine there array of callback bind subscribers. , have 1 emit change, find callback index, , perform callback subscribers.

could point me correct direction.

thanks,