
The pair have been confirmed as Bellamy's new assistant coaches, following confirmation of James Rowberry's departure. Rowberry has stepped away from his role in order to focus on his job at Stoke City, while Piet Cremers also left his assistant role back in July.
Sheehan arrives having previously served as head coach at Swansea City, where he had previously served two separate interim stints.
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He was dismissed from his post in October 2025 following a slow start to the season, and was succeeded in SA1 by Vitor Matos.
Former captain Williams is also a former Swan, having played 352 games for the club.
He was also a key part of the side that reached the semi-finals of Euro 2016, making 86 appearances for his country.
Williams has already been involved in helping out with some of the younger age groups, and will now take on a role within the senior set-up.
The Football Association of Wales has also confirmed Andrew Crofts will be remaining in his role as assistant aoach following his recent appointment at Tottenham Hotspur.
Crofts is balancing his Wales duties with a role as assistant head coach to Robert De Zerbi.
Wales begin the Nations League League A campaign away to Portugal on September 24, before then travelling to Denmark three days later.
They then come back to the Cardiff City Stadium where they play Norway on October 1, before then facing Denmark on October 4.
Bellamy is set to name his squad for the upcoming camp next Tuesday.