Pretty sure they'll just go with the team that is ranked higher if it turns out to be a 3 way tie.
From
https://theacc.com/sports/2017/12/15/MBB_1215171609.aspx
c. If three or more teams are tied in the standings, the following procedure will be used:
1) The combined record in conference games between the tied teams involved will be compiled. Ties will be broken and seeds assigned based on the winning
percentage of the combined conference records. The higher winning percentage shall prevail, even if the number of games played against the team or group is
unequal (e.g., 2-0 is better than 3-1; 1-0 is the same as 2-0; 2-0 is the same as 4-0; 2-1 is the same as 4-2; 1-0 is better than 1-1; 0-1 is the same as 0-2; 0-2 is the same as 0-4).
2) If procedure (1) fails to break the tie, then each tied team’s record shall be compared to the team occupying the highest position in the final regular-season
standings, continuing down through the standings until one team gains an advantage by a higher winning percentage.
3) If the tie is broken by (1) or (2) regarding one or more teams, but three or more teams remain tied, then procedures (1) and (2) will be re-applied among those tied teams only.
4) If two teams remain tied, procedures (a) and (b) will be followed.