I very well may stand corrected, but my understanding is that a would-be 'bidder/predator' would/could essentially 'buy-up' (and/or be in possession of via lending) as many shares as they can within (or below) their overall '$$$ target range' (acquisition budget), potentially triggering a 'compulsory acquisition' (an ASX rule) once breaching the 20% ownership threshold for and/or of a single, listed-entity...
I'd suggest that, if they went down the 'hostile' route, the 'market' would immediately reprice it at a premium (or above) to Merck's offer, which would then force the 'market-players' to establish a 'true, reflective-value' for VLA, which may, or may not be within whatever 'range' a wold-be predator has put on 'controlling' VLA...
Then I guess they write to us making a case for their 'rival' bid, and Merck, having 'matching rights' can respond appropriately, or 'bow-out' as it would be...