Personally prefer pacifier than thumb. Both are actually harmful for their teeth development; try help them to kick the habit of pacifier when they are 3-4yo. Thumb sucking is a habit that is easy to start but difficult to stop or control.
u might wana try using mitten to stop her from sucking her thumb; coz mityen isnt as nice as their fingers. That's how my mom helped a cousin stop the bad habit!
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