Dear Bob,
sorry I did not focus on that post before, it seems it's 100% same as my situation.
And we also are solving the issue by software: we do all things on 1st ADS1248 "forgetting" the 2nd one, then we do all things on 2nd ADS1248 "forgetting" the 1st one.
Next PCB revision I will bring independent MOSI and SCLK to the converters.
Thanks a lot for your valuable support.
My best regards
Paolo