Haruspicy
From Unusual Haunts
Haruspicy is the art of shuffling around your family tree to fit different relatives in to it. These potential relatives will provide one of two types of benefit: either a small passive benefit, such as being able to look after more Poisons, or a one-time benefit, calling in a favour from that relative (and losing your relation to them in the process). An example of each is shown below:
place. holder. tannhauser something or other.
Generally, the more potent the effect of a relative, the harder it will be to fit them into your family tree - after all, everyone only has so much to give, so the fewer people they're related to, the more potent those relationships become.