BACKGROUND According to the kin selection theory, grandparental investment has its evolutionary roots in the individuals’ aim to maximise their inclusive fitness. Owing to an increasing overlap between successive generations in modern affluent populations, the importance of grandparental investment remains high. Despite the growing literature on this topic, there is limited knowledge regarding how the survival status of different grandparent types influences each other’s investment in grandchildren.

 OBJECTIVE The present study examined how the survival status of grandparents influenced grandparental investment among other grandparent types using a wide range of grandparental investment variables divided into two latent constructs measuring relationship quality between grandparents and grandchildren and grandparental involvement in grandchildren.

METHODS We used Bayesian structural equation modeling with multiple-indicator latent variables and the Involved Grandparenting and Child Well-Being Survey, providing nationally representative data of British and Welsh adolescents aged 11–16-years.

RESULTS Maternal grandmothers’ investment was most strongly influenced by whether other grandparents were dead or alive. Living maternal grandfathers and paternal grandmothers had an almost identical positive influence on the investment of maternal grandmothers in their grandchildren. Weaker evidence suggested that living maternal grandmothers decreased the investment of paternal grandmothers and grandfathers.

CONCLUSIONS These findings suggest the opposite influences of the survival status of paternal and maternal grandmothers on their investment. The results are discussed with reference to kin competition and incidental exposure.

CONTRIBUTION The current study represents the first attempt to test whether the survival status of other grandparents is associated with focal grandparents’ investment within and between lineages