without further addition on your part, this thread will be considered as solved tomorrow.

Cheers,
Manuel.

I'm not sure if you are talking about a Mograph Cloner or an Instance with Instance Mode set to Multi-Instance.

For a Cloner Object you can retrieve the matrices inside the MoData like this

        BaseObject *mographObj = doc->GetActiveObject();
	if (mographObj == nullptr)
		return maxon::NullptrError(MAXON_SOURCE_LOCATION);


	BaseTag *tag = mographObj->GetTag(ID_MOTAGDATA);
	if (tag == nullptr)
		return maxon::NullptrError(MAXON_SOURCE_LOCATION);

	// populate the GetMoDataMessage instance by sending a MSG_GET_MODATA
	GetMoDataMessage modataMsg;
	if (!tag->Message(MSG_GET_MODATA, &modataMsg))
		return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);

	if (!modataMsg.modata)
		return maxon::UnexpectedError(MAXON_SOURCE_LOCATION);

	
	// access the MoData from the returned GetMoDataMessage and check its validity
	MoData *moData = modataMsg.modata;
	if (!moData)
		return maxon::NullptrError(MAXON_SOURCE_LOCATION);

	// retrieve the number of Matrix items as well as the array containing the matrix for each of them
	maxon::Int32 matrixItemsCnt = moData->GetCount();
	maxon::Matrix* itemsMtxArray = static_cast<maxon::Matrix*>(moData->GetArray(MODATA_MATRIX));

If you are using An InstanceObject you can check our manual .
As @fwilleke80 said you have GetInstanceMatrices or you can read the multi-instanceData (example in the manual)

Cheers,
Manuel.

const maxon::BaseArray<Matrix>* InstanceObject::GetInstanceMatrices() const

Cheers,
Frank