The max AOS version to support your existing AP platforms are:
- AP-125: 6.4
- AP-105, AP-214/215: TBD (i.e. supported in all current versions)
Minimum AOS version for AP-315 is 6.5.0.0, so you will have an issue running the AP-125 and AP-315 on the same controller.
As you may know, the AP-125 was introduced 11 years ago, and have been EOS for 5 years.