Blue tit sleeping in empty coconut shell

Hello, this is the first time I have written in a chat forum but I am after some advice please. We have hung some filled coconut shells and feeders outside our bedroom window as we are very lucky to have lots of blue tits and Robins visit our garden.

One if the coconut shells had become empty and during the heavy rains we noticed a young blue tit sheltering in it during the night. I have gone to check it again this evening and it is back again! My worry is that its only just perched inside and may fall out and if I modify it slightly, to make it safer (during the day) will I scare it off?

I would really appreciate some advice. Many thanks