The bishops advise banding together if possible:
Independent institutes and monasteries should, when opportune and the Holy See permits, form federations if they can be considered as belonging to the same religious family. Others who have practically identical constitutions and rules and a common spirit should unite, particularly when they have too few members. Finally, those who share the same or a very similar active apostolate should become associated, one to the other.
This makes great sense, but I wonder how it has turned out in practice since the council? Have communities with more contemplative strains kept to this advice with associations? It can be much easier for those with an apostolate in the world to develop ties for practical reasons.