Sorting users in group as per the time at which they got updated in group

Question

Hi There, 
 I have a requirement where i have a process model which contains remove from group and add to group smart services. The requirement is when the process model is triggered by a user then the user name should appear first in the group. Below is my scenario. 
 User1 triggered the process and his name is appearing in the group ( first the remove from group is removing all the users and then this User1 is added, working as required). 
 then User2 and User3 triggers the process model at almost same time with split of second difference, then expected result is the user who has triggered the process latest should has has his name populating on the top but here User2 and User3 are getting populated in the group ( as they have ran the process at almost same time so both got updated in the group ) and now as in group users are sorted in alphabetical order the User whose name in alphabetical order comes first is showing up first rather than the user who triggered the process model latest. I cannot do major changes in process model. 
 Can anyone please suggest a way where we can get the user who triggered the process latest should come first or user who triggered latest should be the only one in the group. 
 Thanks in advance.

Mike Schmitt · Answer

I'm not sure there's a way to handle this purely from Appian's group functionality - even if it does store the date/time that a user was added to a group, I'm unaware of any way to retrieve it. 
 On the other hand it seems to me that it would be fairly simple to build a database-backed back-end for this - in the process model where group membership is affected, also add/update a database table row, which would include things such as the username, the group ID in question, and a date/time column to store the timestamp that any change occurred (perhaps just addition or removal). Then you could query from this database table in any number of ways and have a precise, easy-to-access timestamp ordering of all users in any particular group, and if you do it right, a comprehensive membership history as well (presuming you don't delete rows when a user is removed, but instead have a boolean column representing their active membership in the group).