I also feel that Sridevi and Boney had fought which is why she stayed behind in Dubai when her husband and daughter returned back to India. If she really had to do shopping and catch up with her sister she would have done so but instead she chose to lock herself in the room for two days according various sources. I've read that Sridevi didn't like being alone so why would she stay behind in Dubai all by herself. They are rich people, I'm sure she could fly to Dubai and shop whenever she wanted to but why choose to stay behind all by yourself. I assume during those two days she must have had alcohol maybe because she was upset with Boney which is why they found traces of alcohol in her blood.
I just have difficulty acccepting that she chose to use the bath tub when they were in a rush to go out. If she had used the bath tub after coming from dinner it would be more believable
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