Staying for 6 months

If you are staying for more than 3 months, an application for  Residencia is obligatory.  This may help : https://www.gov.uk/guidance/residency-requirements-in-spain#residency-requirements

Saludos, Darío

No if more than 3 months you should ask for a padron. Only for pensionistas and then have all the benifits of a resident solcial wise.

But if residing more then 183 days a year then residency is a must

Please see extract from UK Gov. link above:

Residency requirements

From 28 March 2007, Royal Decree 240/07 requires that all EU citizens planning to reside in Spain for more than 3 months should register in person at the Oficina de Extranjeros in their province of residence or at designated Police stations. When you register, you will be issued with a credit card size Residence Certificate stating your name, address, nationality, NIE number (Número de Identificación Extranjero) and your date of registration as a resident.

With regards the Padron, you are obliged to do this if you have an address in Spain at which you habitually live - even if it is less that 3 months:

"It is obligatory by Spanish law to register on the padrón at the Town Hall where you habitually reside"

How you register

You don’t have to own your house to register, just have an address where you habitually live, no matter whether you are the owner, you rent, or live with family or friends. Nor is registration a long drawn out registration process. Simply go to the padrón office of your town hall and fill in the form they provide. Take along official identification, such as a passport, and also your NIE or residence certificate/card or passport, a recent utility bill in your name, and the deeds to your house or a copy of your rental contract. Although you may have to return to collect your certificate, the actual registration is completed all on the same day.

You will need a padrón to apply for Residencia.  Residencia will not be considered without it.

Thank you all so much for taking your time to help, I appreciate your advice.