Is there a way of adding tiles to an existing MBTiles?

[carlos-mg89]

I'm trying to merge several MBTiles, using this tool. However, when I open an MBTiles to add tiles to it, it always tries to init the MBTiles file. And I think this is causing troubles in the process of adding new tiles to the already existing file.

Is it possible, or perhaps I'm doing something wrong? Should I create a new MBTiles, copy all the contents of both MBTiles files, and then replace the old one with the new one?

Thanks in advance!