In D&C 107:95 it says that the Presidency of the Seventy choose the other members of the seventy. When new seventies are sustained in General Conference, it sounds like the 1st Presidency chose them. Also, in D&C 107:96, it sounds like there is a limit of seven quorums of seventy. Are there not EIGHT quorums of seventy right now? Thanks.
Let’s read the verses in question first.
95 And these seven presidents are to choose other seventy besides the first seventy to whom they belong, and are to preside over them;
96 And also other seventy, until seven times seventy, if the labor in the vinyard of necessity requires it.
I can’t recall any specific wording during General Conference that would indicate the First Presidency selected the individuals, though I don’t doubt their names would be up for approval by them. After all, the Prophet doesn’t make each and every mission assignment, but he does need to approve them all.
As for the second verse, I could see how you read it as seven quorums of seventy. It could, however, also be read as saying ‘seven times seventy’ quorums of seventy, and the last phrase indicates this possibility; “if the labor in the vineyard requires it.” In other words, the First Presidency and Quorum of the Twelve Apostles are limited in specific number, however the leadership of the church must be able to expand as the Church itself grows, and what I see in this verse is that the Quorum(s) of the Seventy is the area of General Authority where this expansion is allowed to happen.