Nested collapsible elements: initialize a collapsible inside of content for another collapsible

Question

Having a

data-mage-init='{
"collapsible":{
    "collapsible": true,
    "openedState": "opened",
    "multipleCollapsible": true,
    "header": ".parent__collapsed",
    "content": ".parent__expanded"

}}'>

inside of the parent__expanded I need to initialize another collapsible element saying

data-mage-init='{
"collapsible":{
    "collapsible": true,
    "header": ".child__collapsed",
    "content": ".child__expanded"

}}'>

However, nothing happens on the child, while moving it out of the parent's content perfectly works.