Also, don't forget that the bidder here (Brillian/Volaris/Constellation) is on the hook to pay the vendors of their stake the difference between the current offer price and the eventual price of any successful takeover, so they have an extra incentive not to be generous with their offer.
Of course, the ultimate parent is a large, cash-rich and highly cash generative company, so even a substantially increased bid is not particularly material for them (assuming Volaris has their full financial backing). It all comes down to how keen they are to seal the deal - if they are keen, their first (low-ball-ish) offer will not likely be their last, but there are considerable risks to the whole thing falling over too.
