Can non-bread combine with bread towards making one satisfied for bentching?

Question

According to the halachic sources one may bentch once a kezayis of bread has been eaten within 3,4 or 9 minutes.

Source:

Time Limit (min) – How much time does one have to consume the kazayis amount: The consensus among most poskim is that the time of “Kdei Achilat Pras” is 4 minutes, but there are minority opinions that range from 2-9 minutes, and in some circumstances it would be advisable to be cautious for these minority opinions.

Say one is having a soup with a slice of bread the size of a kezayis. Unless he eats very quickly, it would be hard to eat the whole kezayis within the time limitations above. Does this mean that if one ate the meal with the soup but took longer to finish the kezayis of bread then he doesn't need to bentch? Or perhaps you can count the additional non-bread food towards the "satisfaction" criteria that requires one to bentch (veachalta vesavata uverachta).

Answer 1

The Shulchan Aruch O.C. 208:9 writes:

עירב קמח דוחן ושאר מיני קטניות עם קמח של חמשת מיני דגן ובשלו בקדירה מברך בורא מיני מזונות ועל המחיה ואם עשה ממנו פת מברך המוציא וברכת המזון ודוקא שיש באותו קמח מחמשת מינים כדי שיאכל ממנו כזית דגן בכדי אכילת פרס אבל אם אין בו זה השיעור מחמשת המינים אינו מברך לבסוף ברכת המזון אלא בתחילה מברך המוציא כיון שיש בו טעם דגן אף על פי שאין בו כזית בכדי אכילת פרס ולבסוף על המחיה

If one mixes other flours in with flour from the 5 grains and ... makes bread out of it, he makes hamotzi and birkas hamazon. But only if it has enough flour of the 5 grains to eat a k'zayis of grain within k'dei achilas pras. But if it does not have htis amount, he does not make birkas hamazon afterwards, rather he makes hamotzi at the beginning, since it has the taste of grain even though it does not have a k'zayis within k'dei achilas pras, and at the end he makes al hamichya.

Here, even though the mixture is considered bread and you make hamotzi, the other food which is mixed in does not contribute to the k'zayis for the birkas hamazon. Non-bread which is eaten within that timeframe (or even eaten together with the bread) does not contribute to that shiur.