autogenerated/virtual attributes

[btb@bitrate.net]

given an entry such as:

dn=cn=abuse,ou=example.net,ou=mail,ou=groups,dc=example,dc=com
objectclass=mailgroup
cn=abuse
member=uid=jdoe,ou=people,ou=accounts,dc=example,dc=com

i'd like the entry to also include an attribute, generated automatically, based on the rdn of the entry and the superior's rdn.  for example:

dn=cn=abuse,ou=example.net,ou=mail,ou=groups,dc=example,dc=com
objectclass=mailgroup
cn=abuse
member=uid=jdoe,ou=people,ou=accounts,dc=example,dc=com
maillocaladdress=abuse@example.com

where maillocaladdress is the automatically generated attribute.

is this possible?  it seems like something an overlay might accommodate, so i thought i might try experimenting with slapo-rwm, but wanted to also ask here in the meantime.

thanks
-ben