I am getting crazy not knowing the name of the movie.
I watched that movie either in the 80s or early 90s.
I don't know the exact content of the movie. However what I recall is a group of three people - 2 male and one female. I thought the two guys were brothers. There was some kind of battle. The spaceship they had separated and divided into multiple small spaceships.
The model was basically serialized japanified "Star Wars" taking place in a remote solar system (Earth exists but is not directly reachable), with:
Hayato: a Skywalker guy, swept up in a war as his planet is
invaded by the Evil Empire (see below).
Ryu: a Han Solo guy, with all the swashbuckling attributes.
Ape-Man Ballou: a Wookiee guy.
Tonto: a Robot guy.
Sofia: a Princess Lady, but not (directly) in distress as she sails space in an actual unarmed Three-Mast ship.
The Evil Empire: comes from afar like Japan coming into Manchuria, mercilessly exploits the peasants of the solar system and fields a Boss Antagonist with unique powers in each episode. The Top Boss is a mysterious creature driving a non-articulated gigantic golem.
Collapsible swords (no "light swords", but something like a sword made of T-1000 alloy)
Space Combat and hand-to-hand combat in abandoned quarries.
The Hero Spaceship: a donation by The Princess, it can launch two smaller combat ships to engage the enemy individually.
All of the above provided for hours of discussion in school. The daily bosses were quite traumatizing though.
Considering that Star Wars is an americanized Samurai Movie in Space, this kind of inter-cultural ping pong tickles my interest.
A weak connection but I'm reminded of the 1971 movie Silent Running. There is only a crew of 4 (plus robots). Lots of nuclear explosions and the bio-domes on the spacecraft do separate and can fly individually.
Since there is not much to go on (we don't even know if it is cartoon or live action) it could be any number of films or even TV shows. My suggestion is Ulysses 31. With the exception of there being a father and son (rather than brothers), it matches. There are two males and one female and plenty of space battles