We have a company that has supported us in the past. They've been absorbed into a larger company further away that is not interested in supporting us. What do we do with that account? That company technically no longer exists, but I'm just unsure if inactivating is the way to go.
Gawain's thoughts are great as always. Because of Corporate Partnerships, Plans and People I'd add a relationship to the new parent company and reflect the changes in General and Research etc. If there are plans and former employee relationships that may have value to corporate partnerships, (including the "Where do I know that guy from" factor) it might be worth keeping. Check with the Business Development team and if they are a bit and laissez-faire err on the side of caution.
For people who have passed away from us (but their finances have not) we convert them into an estate account. Different because the relationship remains.