A doctor operates 3 clinics using 3 different S corporations. All three had suspended losses from previous years. In 2020 one clinic had income which exceeded its suspended losses, the other two had losses.

Can the income from one S be netted to the other losses even though they have no basis?

In the At Risk rules the three S corps can be aggregated but I cannot find anything that says the S corps can be aggregated for basis limitations rules.

Thank you for reading and any guidance.