How can i push element on array defined on struct in Solidity? - solidity

Question

I'm starting to approach with Solidity (current version 0.8.0) smart contracts, but I can't understand why the compiler print me an error during the push.
The problem is the following: I'm trying to push an element on array in struct but compile failed with error: Copying of type struct memory[] memory to storage not yet supported.
Here my example:
contract TestNFT is ERC721, Ownable {
struct Child {
string name;
}
struct Father {
string name;
Child[] childs;
}
mapping(uint256 => Child) private _childs;
uint256 nextChild = 0;
mapping(uint256 => Father) private _fathers;
uint256 nextFather = 0;
constructor(string memory name, string memory symbol)
ERC721(name, symbol)
{}
function mint(
string memory name
) public onlyOwner {
_safeMint(msg.sender, nextCharacter);
_childs[nextChild] = Child(name);
nextChild++;
}
function mintFather(string memory name) public onlyOwner {
_safeMint(msg.sender, nextClan);
_fathers[nextFather] = Father(name, new Child[](0));
nextFather++;
}
function insertChildToFather(uint256 fatherId, uint256 childId)
public
onlyOwner
{
Child memory child = _childs[childId];
_fathers[fatherId].childs.push(child);
}
}
How can I fix the insertChildToFather function?