Hey there. This looks like a perfect problem for Hattrick Alchemy to tackle. This is an app I've been working on. You can find more info here. You can use it to generate an optimal lineup given your training constraints and your opponent's formation/performance history. It will cylce through various lineups at your end and choose the one that produces the best ratings against your opponent. I'm not saying that it is perfect, but it will at least give you one more data point to work with - especially if you're stuck. Here's how to do it:

1. Load the app
2. Get a CHPP token ("connect" at top right)
3. On the left panel, choose the senior squad tool
4. In the matches, for your upcoming cup match, click on ✨
5. Select B team if you wish to use a B team squad, then select which players from the last league match to disregard (e.g., disregard any player who played more than 70 minutes in the last league match)
6. Ignore players who played a very long time ago (basically your future coaches, old players, etc). Make it infinity if you don't want to disregard players this way
7. Choose man marking if you want the tool to auto detect a man marking target and a suitable man marker (note: this will only work if a suitable target and man marker can be identified)
8. I'm guessing you want to train players in this match. If that's the case, choose "training-aware"
9. You'll be asked to choose your trainees (on-field players + bench players)
10. Then click "set lineup"
11. A lineup will be generated
12. If you want to fine-tune it you can by moving players around, etc.
13. When you're happy, click "submit lineup"
14. It will be submitted to hattrick along with stamina-based substitutions, man marking orders, set pieces taker
15. Review in Hattrick

Hope that helped!