MB4 256b: A Chatzeir Between Two Mavuyos (386:9)

Using a food for shituf mavuyot that you declared will become kodesh when Shabbos begins. Using an item you declared will become chulin when Shabbos begins (machloket Rashi vs. Ritva what the case is). Food that will only become edible after Shabbos begins.

A chatzer which made a shituf mavuyos with the mavuyos on both sides. If the chatzer didn't make a shituf mavuyot with either one does it ruin the shituf for everyone else in the mavui?