Emergency question about voting in Malta!!!

Hi all, soon-to-be first-time voter here. I was under the impression that you could vote for any candidate/s from any party in whatever preference you like (e.g. 1 for a PN MP, 2 for a PL MP, 3 for a ADPD MP, etc.)

According to one of my parents, this isn't the case; they think it's your preferences of the candidates from one party (e.g. 1 for a PN MP, 2 for another PN MP, etc.), otherwise if I do the above, such as voting 1 for a candidate of a smaller party and 2 for a candidate of a larger party, my vote becomes invalid according to them. Is this true or not? Sorry if it's a stupid question and for the tardiness but I wasn't aware of this at all.