The new Kiddush cups we use for Pesach, have exactly the correct Shiur amount needed to comply with the mitzva of four cups. If someone hands tremble can he recite Kiddush and the additional Hagada parts while his cup rests on the plate and he is just holding it so it won’t spill?

Horav Shlomo Miller’s Shlit’a opinion is that it is correct to do so and if some spills after the brocho was said it will not matter anymore.