Are Suwalki/North East Poles Polonised Lithuanians/Balts?

Question for Polish members. Is it true that Suwalki inhabitants have a lot of Baltic blood?

yes, it's quite probable - large swaths of Lithuania have been polonised before like Lauda (polonia laudańska) - it was voluntary polonisation of the nobles (in case of Lauda petty nobles mostly)

Yes, some are. I actually know a family from that region, who consider themselves Polish of Lithuanian ancestry, who continue to maintain certain Lithuanian traditions, even though they have thoroughly polonised over many generations.