XF 1.5 Migration from customized language to child language


Active member
On my first XenForo website i've made the error to install french language and make my edits on the default parent language instead of creating a Child language

Is there a way to migrate from there to a standard child language ? Do i have to start over or can i just set my customised language to use a non-edited parent language ?
I have already installed another default unedited French Language Pack now i just need to know what's the procedure to migrate my old customised language to a child language of this default french language pack