Final personal decision on who to research for summoning(we'd probably take an action next year to get the relic I think?):
Paracelsus - He most likely has a solution to Ilya's problem, though there's not a whole lot of info on him.
Taiyi Zhenren - Very likely to have a solution to the problem, and ALSO sort of an expert on the Third Magic(since that's what he did to revive Nezha). Main complication is he might be too badass.
King Solomon the Wise - While he doesn't have a direct solution in his legend, he's absolutely the man with all the solutions in his legend.
[X] The Ideal Master
-[X] The Ideal Master: Maiya
--[X] Target Master: Yuuno Scrya
---[X] Frame it in terms of the Jewel Seeds. This is an immensely dangerous store of power that claims to grant a wish, but can only unleash utter destruction. This is more or less what he got our children to do for him back during the Jewel Seed Incident, except this time, defensive ability counts for more than offense, and theres none better for defensive power than he does, while his archaeological skill makes him more able to assess if a catalyst is effective or a dud. Everyone would back him up of course. Tell him our own motivations for joining the War, to summon a Caster with the skills to undo the damage that the Jewel Seed embedding had done to Shirou and Rin, as well as help with Ilya's...biological issues.
[X] Catalyst Research
-[X] Catalyst Research: Kiritsugu
--[X] Hero Research: Taiyi Zhenren
--[X] Hero Research: Paracelsus
--[X] Hero Research: King Solomon the Wise
[X] The Changed Uminari
- [X] The Changed Uminari: Kiritsugu
[X] Irisviel: Reality Marble?
[X] Irisviel: Mangaka
[X] Maiya: Illegal Immigrants
@Random Tale
We have 5 more years of prep to the War's start right? IIRC it starts 10 years after the Great Fire of Fuyuki, but I could be wrong.