I think the answer to this is no, but I’m new to this and double checking before I move on.
Let’s say you want to do a food diary base. So there’s a table where each day has its own row, and then there’s a table of breakfasts you typically eat, lunches you typically eat, etc. Each breakfast record, for instance, has fields for a number of servings of fruit, servings of grain, etc. (The Breakfasts table and the Lunches table and so forth are basically copies of each other, because they all have the same fields.)
It works great to link the meals to the Daily table so that a Daily table shows, for instance, a row listing Yogurt and Fruit, Butternut Squash Soup, and Chicken and Rice in the meal cells. This is really helpful! But I don’t think there’s a way to display on the Daily table a total of all the fruit servings for the day. I think (?) there’s no way to basically tell it that the Fruits field on the Breakfasts table and the Fruits field on the Lunches table are the same thing so that it will add them together. You’d have to go in and total them by hand.
In a way, this is less powerful than most of what Airtable can do, but I think this is a thing it can’t do. If I’m wrong, I’d be forever grateful to anybody who can tell me so.
TL; DR: I think linking records from Table 1 and Table 2 to Table 3 doesn’t actually allow Table 3 to show sums from fields within T1 and T2. Let me know if I’m missing it.