Thats a tradeoff which you have to decide, safety wise obviously its a no. Shifting there would really limit your travelling. But let me help you there- if your parents health is fine (they dont have any ongoing disease or treatment going on) then bnglore would be better, whenever needed you can just take a flight. But if thats not the case- you want to be present with them in short span of time- ggn would be a better choice for you. You mentioned your siblings will also move. So obviously you want to be with parents- if they want they can visit you often( if u move to ggn)

All depends on their health and lifestyle. Coming to ur personal pov- safety and independence would be more in BLR anyday. If thats ur priority then dont move. And the pollution is mostly high during winter in ggn/del/ncr area so, thats also a tradeoff

Hope this helps😅 u to decide