Phillips swaps places with Pontypridd coach Simon King who will take up the role of Wales U18 head coach to lead Wales into the inaugural Six Nations U18 tournament in Glasgow in April.
According to WRU elite performance manager Mostyn Richards, the appointments have been made to ensure that elite young players receive access to as much top-level skills coaching and advice as possible at this stage in their career.
"With Wales coach Gareth Jenkins selecting Rowland Phillips (assistant coach - defence), and Robin McBryde (assistant coach - set-pieces) in his national coaching team, we felt it was vital to reorganise the age grade coaching set-up in order that our young, international players gain the maximum benefit straight from the top in terms of technical advice and elite coaching.
"The structure we now have in Wales means that skills coaching and technical advice can very quickly be passed on to our elite young players which is important if they are to develop as professional rugby players.
"The IRB U19 World Championships takes place in April which doesn't pose a clash for Robin with his National Squad commitments. Rowland will provide vital input to the U20 set-up throughout their preparation and competition phases.
Wales U20 (a number of whom took part in national squad training yesterday afternoon, Wednesday) play their first game against the Welsh Clubs XV on Wednesday 17th January.
Mostyn Richards commented, "It is fantastic that some of the boys in the U20 set-up were able to gain the insight and experience of training with the senior side during such a high profile week. I am sure they will benefit hugely from that exposure within the training environment."
The other newly appointed member of Gareth Jenkins, kicking coach Neil Jenkins, will continue to provide expert skills coaching and kicking advice to all key members of the Welsh age grade international squads.
The Wales U19 side kick off the age grade international season today (Wednesday, 2pm) by taking on Leicester Academy at Sardis Road, Pontypridd, in a friendly fixture. They will take on a French Academies side at the same venue on Sunday (kick-off 2pm).
WRU National Age Grade Coaching Appointments
Head coach: Dai Rees
Assistant coaches: Wayne Jones and Rowland Phillips
Conditioning coach: Huw Wiltshire
Team manager: Nick Rose
Head coach: Justin Burnell
Assistant coaches: Gruff Rees and Patrick Horgan
Scrum coach: Robin McBryde
Team Manager: Darryl Hill
Conditioning coach: Ryan Campbell
Head coach: Simon King
Assistant coaches: Gethin Watts and Nicky Lloyd
Scrum coach: Wayne Jones
Team manager: Terry Cobner
Conditioning coach: Dai Watts
Head coach: Dai Rees
Assistant coach: Gareth Baber
Team Manager: David Jenkins