Neither of you should win the argument purely because of position. The height of the line has to fit the pressure on the ball, the pace of the opposition and what the goalkeeper can realistically cover.
The useful conversation is specific. Ask the goalkeeper which balls he expects to sweep and from what starting position. Explain which situations make you uncomfortable as a centre-back. Then agree one or two shared cues: for example, higher when the ball is under pressure, earlier drop when a player has time to play over you.
During the match, one voice still needs to make the immediate call and everyone has to respond. That can be the centre-back on the line with the goalkeeper supporting behind.
A good compromise is not 'split the difference by three yards'. It is agreeing the situations in which the line should change.
