It sounds like your grandmother was trying to encourage your adult relatives to be mindful of their actions and the impact they have on others. It's possible that she was trying to caution them against getting in the way of or hindering good things from happening, or perhaps she was trying to encourage them to be more proactive in bringing about positive change.
It's also possible that she was trying to encourage them to be more mindful of their own mortality and to make the most of their time on earth by doing good and helping others. Ultimately, the message seems to be one of caution and the importance of considering the consequences of our actions.
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