According to the rules :

• You cannot move a unit such that it would be in base contact with multiple enemy units–effectively starting a melee.
• It is possible to be in a melee with multiple units if another unit joins later.

1) As below Luke engaged my stormtroopers so I retaliated by sticking vader into base contact with Luke. Is this legal? Seems to me according to the rules its ok (quoted above)

2) when Luke retaliates and causes wounds, who suffers them; stormtroopers or vader? (both previously wounded. Storms lost 3 vader 2)

3)Vader clambered to get up there. Does relentless follow a clamber? Seems like clamber is a move according to the rules.

Tldr is this situation below legal?

52 minutes ago, Alan Noir said:

According to the rules :

• You cannot move a unit such that it would be in base contact with multiple enemy units–effectively starting a melee.
• It is possible to be in a melee with multiple units if another unit joins later.

1) As below Luke engaged my stormtroopers so I retaliated by sticking vader into base contact with Luke. Is this legal? Seems to me according to the rules its ok (quoted above)

2) when Luke retaliates and causes wounds, who suffers them; stormtroopers or vader? (both previously wounded. Storms lost 3 vader 2)

3)Vader clambered to get up there. Does relentless follow a clamber? Seems like clamber is a move according to the rules.

Tldr is this situation below legal?

1) Yes, if a unit has a melee weapon, it can enter a melee (as long as it does with only one unit as you quoted with the rules). It doesn't matter if the unit you're engaging is already engaged with another of your units.

2) Before rolling dice Luke has to tell which unit is attacking, like a normal attack, nothing changes.

3) You're right, clamber is a move, and as Relentless triggers after a move action, you can use it.

1 hour ago, Lemmiwinks86 said:

2) Before rolling dice Luke has to tell which unit is attacking, like a normal attack, nothing changes.

Cool cheers. We just rolled a red D to decide as we couldnt find it in a reasonable timeframe