This comes across as a misunderstanding of premium pay differences between reserve and line. A line holder gets double pay for a premium trip in most cases. A reserve gets pay above guarantee and a payback day in lieu of double pay.

How do you propose implementing payback days for a line holder? Would they get single pay and a payback day instead of double pay?

Reserve should have access to silver slips just like they have access to all other forms of premium pay via IA, GS and QS. SS is discriminatory against reserves.