The eighties saw several (real) "gestalt" anime series released in the United States, where multiple shows were combined and highly edited to create a new show that met the number of episodes required for US television. Harmony Gold put out Robotech and Captain Harlock and the Queen of a Thousand Years. World Events Productions put out Voltron.
And SylverRhythm (as I'm now spelling it) put out Soldiers of the Sun.
Soldiers of the Sun combined Lost Whispers, Magic Soldier Princess Z, and Destiny Police into one series. Even though they were unrelated (and took place in notably different settings), connecting dialogue and "careful" re-editing of scenes combined the shows.
Each of the three series represented a "generation" in the show -- Lost Whispers being the "Ancient" generation, Magic Soldier Princess Z being the "present" generation, and Destiny Police representing the "future" generation.
Lost Whispers was minimally changed - with "Dark Mephisto" being renamed "Lord Hush" and the Seven Swords of Light were said to combine into the "Sun orb" (a wholly unique concept to Soldiers of the Sun not present in the original show). The events of Lost Whispers largely played out as normal, with the ambiguous setting of "the ancient past" (onscreen it says "hundreds of years ago" while later dialogue will refer to this timeframe as "many millennia ago"). Dark Mephisto/Lord Hush is banished to the netherworld, and our heroes remain triumphant.
Magic Soldier Princess Z followed Lost Whispers, with Yoshiko being renamed "Kelli." The flashback scenes of the Ancient Kingdom and Yoshiko's/Kelli's past life are said to be in "the final era" of the same kingdom as Lost Whispers (which is slightly incongruous as the two don't look remotely alike), and the "Z Emerald" which transforms her into Princess Z (or "The Ultimate Sun Soldier" as Soldiers of the Sun refers to her as) is now refered to as the "Sun Orb" (mentioned in the earlier generation).
The Hush (who get to keep their name) are said to be the descendents of Lord Hush, invading not from space, but instead the netherworld. Lt. Tanaka (Yoshiko's/Kelli's love interest) gets renamed "Captain Lloyd Rayburn" as well.
Finally, the Destiny Police portion of the show is said to be set forty years after the events of Magic Soldier Princess Z. General Yamazaki is turned into General Rayburn -- who is said to be the same character as Lt. Tanaka/Cpt. Rayburn. Where the robotic arm from Magic Soldier Princess Z went was never explained (episode 3 of Destiny Police shows the General without his shirt in a single shot -- where he has two intact arms).
"Kelli" is said to have passed away, and "General Rayburn's" daughter "Sally" (Kasumi in the original and part of the Destiny Police force) is stated to be Kelli and Rayburn's daughter (although no familial relationship exists in the original series between Yamazaki and Kasumi).
The "Shadow Force" from Destiny Police get combined with The Hush, and Akira Takei (Now "Jason Baxter") was now experimenting on the "Sun Orb" to split its power into the weapons used by the "Soldiers of the Sun" (nee Destiny Police). Other major changes include the General reaching out to Baxter to create the weapons (instead of vice versa), and the removal of the the General's "dark past."
On a footnote, SylverRhythm let their license lapse on MSPZ - which then got picked up by a rival company... making re-releases of Soldiers of the Sun awkward. SylverRhythm has paid to animate "bridging scenes" with original footage to connect the "Ancient" and "Future" generations (combined with narration), but it gets super awkward.