Great that you do that. Sad that you have to do it every week.
I'd have you on the selection panel any day of the week. Basically if you pick the second's opener for the firsts and bat him at 8 you're telling him he's not up to it - pointless and bad man management.
I was chairman of selectors at our club for a number of years and had to do a similar arguing spot.
I had to get the captains who were short to say where the gap was and fill it accordingly.
If an opener wasn't available. Take the 2nd team opener or move someone up the order and take a middle order player instead.
Also think of where they'll do most good for the team. For instance, if you are taking someone to bat at 8, take someone who can do that and field really well. No point taking the old man who can run but can bat.
You also need to balance expectations of 2nd teamers and if they do it for a couple of weeks, swap them with another for a couple of weeks.
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