The processes and sub-processes list by user or PID

by PID:
pstree -p -s 8227

output:
systemd(1)───clamd(8227)─┬─{clamd}(8317)
└─{clamd}(10786)

by user:
pstree -aps username

output:
imap,29713
lsphp,4612
lsphp,11974