I strongly urge the Beth Din to consider returning to the original custom of only one person saying one kaddish per service
If piyyutim can be omitted on the yamim noraim (which is a custom), then my suggestion must also be discussed seriously
The common practice of multiple people saying kaddish together is halachically unsound as you are well aware
GGBH does this
In Israel, the western Ashkenazim (yekkes) do this
So do the Zilbermans
The original custom is making a comeback in many other shuls around the world
Also, in all Yemenite communities, only one person recites kaddish
In these congregations, no bickering takes place because they never saw a reason to go along with this innovation
There is no reason why the United Synagogue can’t reinstate a practice that was followed up until WW1 (as seen in the earliest editions of the “singers” siddur)
Or better yet, you could tell your followers to make aliyah and set an example by doing so yourself
Sincerely, Joshua Shalet, a Torah Jew