The role of groups in a user migration across blockchain-based online social media

User migration is one of the main phenomena occurring on modern online social media. And, it is even involving the most recent alternative paradigms of online social media, such as blockchain online social media. In these platforms, user migration is strongly linked to the hard forks of the supporting blockchain, i.e. a split of the original blockchain and the creation of an alternative one. Our understanding of user migration is still limited, especially when we look at it from a network-based standpoint. What is the role played by densely connected groups of users during user migration and fork events? Are there differences in the network structure of groups of users who stay and those leaving for a new platform? Guided by these questions, here, we show, through a network-based analysis rooted in the identification of communities on multi-layer networks, that i) the "position" of a group within the network of social and economic interactions is connected to the likelihood of migrating, i.e. marginal groups are more likely to leave; ii) users in densely connected groups interacting through monetary transactions are more likely to stay, and iii) user migration differently impacts on the network built on social interactions and the network based on monetary transactions. These findings highlight the importance of social and economic relationships among users along a user migration caused by fork events. In the general context of online social media, it motivates the need to investigate user migration through a network-inspired approach based on groups.