SPL age restrictions currently prevent clubs fielding anyone over aged in the Under-19 league.
An SPL spokesman said: "The managers feel there should be one league between the youth initiative and the reserve league."
Many managers have also called for the scrapping of the SPL's controversial Under-21 rule, which forces them to include a certain number of young players in their matchday squad.
The SPL spokesman added: "It's a live issue we are pursuing at the moment. We have got a group looking at it."
It is understood the SPL would scrap the rule if all their member clubs agreed to do so.
Thursday's meeting was also attended by Scottish Football Association head of referee development Hugh Dallas, who reiterated his eagerness for managers to contact him with any grievances they may have over the performance of match officials.