There is (still) no best theory. However, you can develop one looking into real cases, for example, assembled in Holtbrügge, Dirk / Haussmann, Helmut (Eds.)
The Internationalization of Firms. Case Studies from the Nürnberg Metropolitan Region . 2. Aufl., Augsburg et al., Rainer Hampp Verlag, 2017
Many firms presented in that book are family-own and family-run firms.
Im taking in my research the importance of internal factors of family business as: social capital, ability and willing to innovate and other factors but Im confused of choosing the innovation model that fit to developing countries
In relation to innovation, the fact that the company is familiar does not represent anything different in relation to the others of its size and area of operation.