Hello,

it is possible A1/Master and A2/Slave and the switch to A2/Master and A1/Slave.

But:

Recursive synchronous operation interconnection

A recursive synchronous operation interconnection is present when, in a single synchronous

operation relationship, a synchronized axis is interconnected directly or indirectly again as a

master value via other technology objects. A synchronized axis cannot act as a following

axis to a master value and as a master value for the same axis simultaneously. Recursive

synchronous operation interconnections can result if, for example, a synchronous operation

relationship is to be switched over in the event of an error. Also refer to the section titled

Error handling in the user program (Page 137).

1.1 Overview of synchronous operation

https://support.industry.siemens.com/cs/ww/en/view/51770750