[quote=@Unoedipal]
<Snipped quote by IncredibleBee>

How are they linking up to the Grail?

At that point you're better off just having your own Greater Ritual to summon a Servant.
[/quote]

That primarily depends on how you want to play the mechanics of the Grail's prana supply. Linking to the Grail shouldn't be too difficult at this point, as, after all, this is the 726th time it has manifested - there should be some knowledge by now of how to link rituals into it, but little information on how to draw out of it (other than winning the war). Perform the summoning ritual along with the ritual to funnel the prana and you've got yourself a Servant.