I have a question about attacking using sea transport. I illustrate using the attached picture.

The knight unit circled in green is attacking starfall using ship transport, that cool and all but the question is:

Can the ship circled in blue in the east summer sea support it for the attack on starfall?

We had this question because the manual is not clear about this and it does not totally make sense, how can the ship circled in blue offer transport and then support all the in the same turn?

Transporting units via ships is not really an order for the ships. The ships only make the connection, there is no actual "march" order placed for them, the order is placed for the land units. So if there is no other order placed for that particular sea unit you can use it for support.

Mechanically, it works differently from Diplomacy - where you can only do one or the other, and you have to Order a Fleet to Transport an Army.

Thematically, they are Fleets, not single Ships - so some of them Transport, and some of the Harrass the Coastal Villages.