Impossible to know how much insurance she had. Highest limit on a policy in MA is 250k per person, but I'd expect her to also have a personal umbrella policy, which usually start at 1 million. If only because she was a solo homeowner, and as a financial analyst whe was probably pretty savvy about such things. We really can't say for sure though.
We also have no idea how much liability coverage either bar has, but likely each have at least a million, probably more given their dram shop exposures.
MA has a "in for a penny, in for a pound" joint and several statute. Which means if all three parties are found partially liable, they'd contribute equally to any judgement. Insurance limits aside.
With that said, it would be difficult - if not impossible - for the bars to separate their lawsuits from Read's. Courts usually prefer consolidation. And given the NGs on the criminal counts, I don't think it would benefit the bars to do so. If Read didn't hit anyone that night, then the bars have a causality defense. The four necessary elements of negligence are: 1) There had to be a duty owed, 2) There has to be a breach of that duty, 3) There must be damages and 4) There has to be causality between the duty breach and the alleged damages. All four elements must exist for their to be a liability finding.
If we go through the negligence elements for the bars: 1) Yes, the bars had a duty not to endanger lives by overserving a patron. 2) They potentially breached that duty if it's proven they overserved Read. 3) As the plaintiff lost his life, there are damages. 4) (Here's where it falls apart for the estate) If Read did not strike John O'Keefe with her vehicle, there is no causality between the breach and the damages.
The cases against the bars are very much connected to case against Read. If she didn't hit JO, they can't be liable for his death.