Ann: Rex enters a A$393M Scheme Implementation Deed with MACH, page-94

A scheme meeting requires approval by (1) 75% of shares voted and (2) 50% of shareholders voting.

What I'm not sure of is whether MACH's already-owned shares are votes. If they are buying on-market from small holders, they are likely to be reducing the number of holders who would vote YES under criterion 2. That's probably true no matter which large holder is buying from small holders. If non-related parties are buying up shares with intent to support the scheme (this was my naive assumption), it's bolstering the 75% side of criterion (1) as it ensures the shares are voted, not forgotten in a bottom drawer.