Questions about member expression

I would like to know the appropriate member expression for the Account “ACH0035” as it differs from the expected value.

I can use @PRIOR(“ACH0035”) to get the value of its own previous month,
@PRIOR(“ACH0035”->“Mar”,1,@CHILDREN(“All Years”)) cannot get the value of March of the previous year in case of April.

The member expression for “ACH0035” is as follows
IF(@ISMBR(“Apr”))
@PRIOR(“ACH0035”->“Mar”,1,@CHILDREN(“All Years”)); /Opening balance of cash and cash equivalents/
ELSE
@PRIOR(“ACH0035”);
ENDIF