Here is the step by step :
1. Make sure to go to the Bar to meet Liz for the first time to trigger the next event
2. Go there again on Tuesday to catch Anna and Liz having conversations together. Do this 3 times ( 3 Tuesdays ) until Anna invites Liz to go to the Hotel
3. Go straight to the Hotel to unlock the threesome event with Anna and Liz ( Unrepeatable )
4. Visit the Bar on any day to meet Liz and you'll get 2 scenes with her ( Repeatable )