It’s quite exciting topic 🙂
Multihoming is when a host or network is connected to one or more (multiple) Internet Service Provider (ISP) or we can say it has multiple up links.
As by know there are few RFC for multihoming approach such as from RFC7157. Try to read it for list of scenarios and also techniques. For know I just want to achieve load balancing over the multiple up-links, or at least have fail over.
At first I decided to have topology like the diagram below, two ISP connected to a single home router, the host then can connect to this router and will be assigned at least two IPv6 addresses from only one network interface.