While I certainly do not have all the facts, it appears that the estate lawyer thought this created what is known as a technical termination. In these cases, the partnership will retain the same EIN and there are in fact two separate tax returns filed using the same EIN.
Unless the will had a pecuniary bequest and the transfer of interests was to take care of that bequest, I don't believe a technical termination was correct.
Regardless, I would just include each K-1 separately for the technical termination year. The IRS will receive a copy of each K-1 as well and if you combine them it may cause a matching issue.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
