Q. Regarding the issur of mashkin shzavu of grapes on Shabbos, If one has a fruit salad of grapes and other fruits, and there is a collection of liquid at the bottom of the bowl, is the mashke mutar btaruvos? Do we go after rov fruits i.e. rov grapes assur, rov melon muttar?
Thank you

A. Shulchan Aruch and Remo (O.H. 320: 1) rule that the juice that seeped by itself from grapes on Shabbos is rabbinically prohibited. However, from other fruits even if they are also regularly also squeezed for their juices, it is permitted.
Shulchan Aruch (ibid. 2) also rules that a barrel of wine that contains some grapes does not become prohibited, although the grapes split and release fresh juices into the wine on Shabbos. Mishna Berura (ibid. 14) explains that the reason in the bitul or nullification of the emanating juice in the at least sixty parts more of extant wine already in the barrel.
Piskey Teshuvos (New 75 edition 320: 3) quotes different opinions in regards to the need of shishim (sixty parts) and the grape juice remaining visible after bitul, and rules leniently, (since every minute amount of juice that seeps out becomes immediately mixed and nullified, it will not “awaken” later on.)
Horav Shlomo Miller’s Shlit”a opinion is that, in your case (even if mixed with other fruit juices) you would also require a shishim amount to permit the collected juices.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a