The Franken camp filed today a "Contestee's Motion to Amend Answer and Counterclaims". The gist of this motion is that (a) Franken included with his counterclaims a list of absentee ballots that he believes should be counted, and (b) he would now like an opportunity to add to that list.
Without even seeing Coleman's response, I predict this motion, in its current form, will be denied.
For starters, Franken has not proposed specific changes or additions; he wants to keep it open-ended until three days before Coleman finishes presenting his case. The judges however will want to keep a tight reign on the proceedings, and will not approve an open-ended amendment. Before approving anything, they will want to see the proposed amendments, written out in ready-to-file form.
In addition, on a procedural level, I would predict that the court will go in the exact opposite direction. Instead of allowing Franken to keep his case open-ended, the court is likely to require Franken to present his case at the same time as Coleman, i.e, when Coleman calls a witness to go over ballots or other issues, the Franken campaign will be required to present its ballots and other issues that need to be covered with the same witness (instead of calling the witness back later). This will help shorten the trial and minimize inconvenience to the witnesses.
It may be that Franken will not be allowed to add to his list, even if/when he does propose specific changes. But if the court does entertain an amendment, I predict he will have to present his proposed changes sooner rather than later, in order to allow Coleman an opportunity to prepare a rebuttal of these ballots.
I may add to this analysis later an estimate of the number of absentee ballots that might potentially be counted, but that's it for now.