Denise, I know exactly what you want to do but you have to accept it, you cant. There are no specific dates for your 180days, it starts on the day of entry into Spain. So if you stay 90days in 1 go you must return home to fulfill the rest of the 90days out of the 180days not in the country. If you try to extend your stay you are not only illegal but could face heavy fines, deporting and worse barring you from re-entering for a long period. This does happen! You could apply for residencia immediately after staying 90days and would have proof of application so those things would not happen until residencia completes, but that is the only way to stay legal over 90days. Oct -Dec, is the first 90 days out of your 180day period, so you must go home for further 90days from the date you entered Spain in October, you cant run them together. Then after 90days out, return anytime to suit you but remember if you want to return Oct - Dec dont pay a visit within 90days of your October date as that entry date will start a fresh 180days and ruin your ability to stay later. I totally get it and it needs careful timing to get out of it what you need, but so sorry, like myself you cant stay more than 90days continuous without residencia. I,m doing Mar-Jun and Sept-Dec, cos I want summer stays, will lose out 3mnths of heat but rest is ok.😢😢😢
Pauline