Roberto, Happy new year to you
Section 16 (2) of the HPA establishes:
The notice shall include the items to be dealt with, the place, day and time of the first call and, where applicable, of the second call
As it was stated by the Supreme Court in 20th Nov 2006 resolutions of the Owners’ Committee not included in the Agenda are challengeable. Therefore, it is necessary to attack those resolutions at Court; meanwhile they are valid and enforceable.
The point is to include the business in the Agenda, if so; it is also valid to pass that business at the question time
Regarding the term to challenge section 18 (3) provides:
The action shall lapse three months after the adoption of the decision by the Committee or one year in the case of resolutions contrary to the Act or against the Articles. For owners not present at that meeting, this time limit shall begin to run from the date on which the notice has been received, in pursuance of section 9