The first is in Surah Nahl, the context is about relying on God, part of relying on God per the verses is to ask the family of the reminder if we don't know, and then talks about the role of Mohammad (s) in this regard, in explaining and making clear what has been revealed from God.
Therefore to rely on God is to hold on to both Quran and Ahlulbayt (a).
The second is in Surah Anbiya, the context is about miracles, disbelievers are saying why isn't Mohammad (s) sent with miracles like previous Messengers which is a false propaganda since he is sent with miracles that are even more bigger and clear then previous Messengers. It says in this context go ahead ask the family of the reminder (for miracles) if you don't know. The Surah goes on to talk about Isaac (a) and Yaqoub (a) with respect to Ibrahim (a) and they all being Imams who guide by God's Authority/Command.
In Surah Nahl, also "clear proofs" was mentioned. So we can see Ahlul-Thikr (Reminder's family) know how to explain the Quran and guidance, and are to be relied on to understand Quran as well all can perform miracles like the groups of men previously sent as "family of the reminder" of the past.
It also shows the family of Musa (a) and Harun (a) was such a family and Isa (a) is of that family and Elyas (a) is of the family because with singular "you" addressed first to Mohammad (s) and then plural you, it's saying say for the sake of argument Mohammad (s) you were ignorant or need of guidance and didn't know the truth yourself, you would be required to go the family of the reminder of the past, but surely, you and your family are the family of the reminder of the time and final one.
We can combine with other verses that say to ask previous Messengers sent if God ever commanded to worship other gods or those given the book if he was in doubt, that if Mohammad (s) was not a true Messenger, still, there needs to be revelations and a family linked to that reminder in those revelations.
That which Quran reminds of is the Welayah of God's Kings, and previous revelations did the same, the light of God's anointed kings is called to by all scriptures from God.
So we can see Quran is saying this is a structure of guidance - and if his revelations get corrupted and the foundations of religion fall, God revives the religion through a Prophet and appoints the founder with successors.