I think it is better not to juxtapose negotiation of meaning with sociolinguistic and strategic competence. As for the two competencies, surely there is a mutual relationship between them. If you know the sociocultural aspects of the target language, you can make the most of your strategic competence AND if you are strategically competent, you are better equipped to account for the sociocultural aspects of the TL.

I am of the view that negotiation of meaning which has been proposed by Michael Long within Interaction Hypothesis can be used as a type of strategy to compensate for the linguistic (and even) sociolinguistic inadequecies. Although daunting. it seems that some relationships between them can be traced.

Yes, there is a mutual relationship.

Thank you!

So among others:

Long (1980) defined negotiation of meaning as the interactional modification performed by interlocutors, the use of various communication strategies that overcome a breakdown in communication.  Later, Tarone (1981) identified negotiation of meaning as the interactional function that differentiates communication strategies to production strategies.  Canale (1983) stated that the use of effective strategies in negotiation of meaning is an element of strategic competence.

Is it fair to say that negotiation of meaning is the link between the sociolinguistic competence that creates it to the strategic competence that is utilized to achieve it?

As far as I understand, negotiation of meaning cannot be considered a link between sociolinguistic and strategic competencies. Nevertheless, we could safely argue that during the negotiation of meaning both interlocutors draw upon their afore-mentioned competencies to compensate for their lack of knowledge/ability regarding grammar and vocabulary of the L2 (linguistic competence)