Following how it was worked once ...
If a system is fully reworked and your RP can help with it, you can freely ask for movement of a base, since Sigma-15 was fully reworked then you could ask a free move on your base, that was done if i am not wrong on 5.1, its been a lot of time, where you has been all that time?
Sadly, once a Siege is declared you cannot make such request (as it will increase the siege time and will not do anything good to your base...)
Bundschuch has some enemies, those are the following:
ENEMIES:
Corsairs, Unioners, Rheinland Authorities, Rheinland Corporations
Man, try all your resources and media available to attract attention, put a bounty on their heads, pay for defense, get help from whoever you want, deal with the attackers, at siege time, you can have plenty of options at your disposal ...
What you said about Insurance is right, but now the siegers take a cost (using Borer Rounds cost and cost greatly), so both have some suffering....
If i were the one giving insurance i would take, only to return at most Core 2 bases with some random modules built in there so you don't start from scratch but need to get things going all over again, and rest is up to you, insurance should be made to recover some of the credits or partially a base so don't hazzle with rebuilding it all over again, not to fully recover a damn base i sieged and getting it back again and again and again ¬¬
I would tell you what you can do and you must choose one ...
Ask Lawful Enforcement with SOS call ... Send a message and wait till they respond ...
Ask Friends to hand in against your attackers, even a distraction in time are precious time they would be doing nothing ... pack a full unit of bombers and land hell to them, or bring small swift capitals to get it appart from your base.
Deal with the attackers, talking is how people understand, open a comm channel and try reach an agreement
Buy transports and load them and on no siege timers, move all things from your base if you deem it lost so you only lose material and time, but not your money, your assets and all of the cargo onboard ... this is a thing,
Put a ridiculous high bounty for any kills over the period of siege against them ...
Some other people prefer lose a base, and just rebuilt it in other place continuing on the story ... or saying something happened
Build damn Weapon Platforms, those will not stop the attackers but will eat energy from their cores making them less shots per time (and since now they are mirrored meaning you put 2 platforms in one slot in the opposite site or so) can make it better defense if placed tight
Request help from enemies of them ... Call the Corsairs, Unioners, bribe them, offer something in return or something ...
Those are some, but there a plenty of things, instead of crying, asking insurance or a move long time after the system changed ... and on siege timer already declared
So it would be better start working on one of them or everything at a time, take all your chances and join too in the defense of your base and with some people that would be a huge clash of sides ...
And another thing, admins did not cause the issue, your leniency of not taking care or something goes wrong there ... if you has a base you have responsabilities, and should know how this work this
Since siege already started then is gonna be literally zero possibilities to make it happen, your options right now are written above, if your base survive (i hope it do) then could write a RP about moving base or so, but since it was your responsability (man, check the navmap at least and see if something is wrong it your base and so so you could ask it timely ago)