Andy Frampton returns to the club in a coaching position, while two more take on new roles within the Academy
Millwall have appointed Justin Skinner as the club's new Elite Development Squad manager.
Skinner had previously been working as U18s boss, assisted by Dave Livermore, but has now filled the position vacated when Neil Harris took over as first team manager.
Elsewhere, ex-Lions defender Andy Frampton is returning to Millwall as a development coach. In what is the 35-year-old's first such role since calling time on his playing career earlier this year, Frampton's position will involve coaching at first team level as well as for the club's Academy sides.
Larry McAvoy, who has been working in Millwall's Academy set-up for 12 years, most recently as U16s boss, will take on the U18s group. Working together with McAvoy will be David Connolly, the former Wimbledon, Sunderland and Southampton striker, who has also played in a World Cup for the Republic of Ireland.
"We're delighted to be able to announce these exciting changes after what was an extensive and thorough recruitment process," Academy director Scott Fitzgerald told millwallfc.co.uk.
"Justin has done a fantastic job since he first joined the club and many of the players he has coached are now playing week-in, week-out for the first team.
"It is great to see Andy back at Millwall. I know he looks back on his time at The Den with a lot of fondness and he will bring fresh ideas plus vital experience of playing for the club into his first coaching position."
Discussing the changes to the U18s group, Fitzgerald added: "I've worked with Larry for a number of years now and his abilities as a coach are absolutely superb. He has worked incredibly hard since first moving to Millwall and the U18s position is a great platform for him to impress further.
"David is excited to get going in what is his first coaching position. His experience as a player is amongst the best, though, having played for many years in the top flight, as well as in Europe and on the international stage with Ireland."
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