Over the last several decades an on-going interest by academics in studies of intra- and inter-personal relationships has revealed complex and dynamic decision-making mechanisms within households. However, previous research has mainly focused on the relationship between partners/spouses in households of couples and/or nuclear families. The intra-household dynamics in household contexts other than couples/spouses and inter-personal relations in these other households remain largely unknown. This paper is therefore dedicated to investigating the intra- and inter-personal interactions of partners/spouses and inter-personal interactions between different generations in elderly co-residence households. Using data from the Nanjing Residents Travel Survey 2012, an asymmetric structure is observed among the interactions between young females and males: males' activity participation is more strongly affected by females' activity engagement than the reverse. The presence of an elderly mother or mother-in-law tends to reduce the interdependence of intra- and inter-personal interactions for both young couples. It is interesting to find that a young female's activities are more determined by her elderly mother in the extended family than her husband. The influence of a young spouse on an old mother's activity participation is also gender-specific. Implications of these findings for public policies are also discussed at the end of the paper.