@Guti, you have 2 problems. One it's that you can't move with family to other country. This is the big one. The second it's that actualy you are in a comunist country. All will be wrost from now.
Meanwihle you will be resident in Spain you will have problems. And I'm conscient that Spain is the best country on the world to live. Well it was !!!. But right it's imposible to think about a future there working or having assets.
But if you can't go out, and you can have the posibility to open an office, and employ worker, you can have a small oportunity to reduce taxes legally. But not anonymously. For that you would need to create a structure for exemple in CY with trustee.
If you can have 1 employee you can try to open a company in Madeira. You will pay 3% taxes. And if you are in a Special industrial zone in Funchal, you will pay 1/2 of 3%. You need to invest 75K in your business but not obligatory in the island, and the directives and decisions must be taken from a person who is resident on the island and all the direction must be done from the island. Your employee can do it. This advantage are limited on the time. This structure has a caducity. It remain 9 years. After this time the EU wil decide if they stop this special traitement or if they give some years more.
You have the same advantage in Canary Island. There in the small island you need 3 employees. Is named the ZEC. Zona especial canaria. But it's not a sepcial zone. Is all the islands. On the big island you need 5 employees.
Tax are 4%. Completely legal and acepted by the european union. No TVA. Only IGIC with 7%.
Canary has the same problem than Madeira. In 9 years the caducity of this previlege will arrive. No body know right now if it will be renewal.
But If you business is for IT, in Georgia the special zone for IT business is free tax. To pulish that and if you can, you can try to have substance. It's not obligatory. You rent a flat less than 200€ and put an employee 300€. There is not social security in Georgia. Is the best country to get substance very cheap.
In the case of Georgia you will need also to find a system to find a trustee if you don't want to be visible as UBO. But this is other history.
But after all that, in your place, I should beguin seriously to think to convince my family little a little to change the residence one day. Better in short time that in long time. In Spain is better to saty as emigrant or visitor than as resident.