I ended up doing a simple javascript match as I could not come up with a clever clean solution:
// I build up a string that I want to replace the old string with
// create a list of the ids that I wanted to append
listOfIds = ""
arrayOfIds.forEach (id) ->
listOfIds = listOfIds+id
// grab the old link in it's entirety
oldLink = $("#done-button").attr("href")
console.log(oldLink)
// grab the string from the old link I don't want
match = oldLink.match(/(?:group_id%5D=2)(.*)(?=&group=)/)[1]
// replace the old string with the new string
newLink = oldLink.replace(match, listOfIds)
// changed the href attribute on the link
$("#done-button").attr('href', newLink)