With several players in contention for inclusion in Munster's Heineken Cup quarter-final squad, Costello has delayed finalising his team for the interprovincial clash.
If Danny Barnes is not required for Easter Sunday duty, he could team up with Hanrahan for the 'A' side at the RDS on Friday evening.
Munster 'A' face a fairly daunting task against what looks a particularly strong Leinster 'A' side that will be captained by the Ireland-capped Rhys Ruddock.
"Of course it's a huge ask to travel to the RDS to play the favourites. But it's a challenge that we're really looking forward to," admitted Munster 'A' boss Costello.
"We have a quality squad, we have worked extremely hard to get to this stage of the competition and there is real excitement building amongst the players.
"Leinster 'A' expect to have massive support on Good Friday at the RDS, and whereas we can have control over what happens on the field we'll be looking to our supporters to turn up in numbers and maybe give us the sort of lift that Munster supporters are renowned for."
MUNSTER 'A' Squad (v Leinster 'A') - Backs (10): Sean Scanlon (Cork Constitution), Ronan O'Mahony (Garryowen), Luke O'Dea (Shannon), Ivan Dineen (Cork Constitution), AN Other, JJ Hanrahan (UL Bohemians), Declan Cusack (Garryowen), Scott Deasy (Cork Constitution), AN Other, Cathal Sheridan (UL Bohemians).
Forwards (12): Dave Kilcoyne (UL Bohemians), Denis Fogarty (Cork Constitution), Sean Henry (UL Bohemians), John Ryan (Cork Constitution), Peter Borlase, Brian Hayes (Cork Constitution), Philip Donnellan (Cork Constitution), Ian Nagle (Cork Constitution), AN Other, Brian O'Hara (Cork Constitution), Barry O'Mahony (Clontarf), Paddy Butler (Shannon).