I'll keep the thread updated.
After almost five months in the shipyard and one month waiting for me to rig it, the SC15 was officially re-launched last sunday. The glass/foam/gelcoat job looks impecable, with a mirror-like finish. My daughter had to ask what side broke for she couldn't find it simply looking and feeling.
Unfortunately I have no pictures. The last months were very busy and I could only visit the boat twice and didn't have a camera with me.
Still, AFAIK it was fixed using the drawings I made based on the instructions and techniques received here and from Tom Haberman - many thanks to all of you!
I tried to post the drawing and instructions here but (for obvious reasons) they are in Spanish and the max size makes the image fuzzy. Anyway, it gives an idea of what to do and anyone interested can get the uncompressed file from me.