private int getOrdinal(String fieldName) throws NotFoundException {
		if (!isContainer()) {
			throw new AssertException();
		}
		Composite composite = (Composite) memberDataType;
		int count = composite.getNumComponents();
		for (int i = 0; i < count; i++) {
			DataTypeComponent component = composite.getComponent(i);
			if (fieldName.equals(component.getFieldName())) {
				return i;
			}
		}
		throw new NotFoundException();
	}
Replace existing member with newContainerMember
@param fieldName name of existing field (used to locate union member)
@param newContainerMember container replacement member
Ghidra/Features/PDB/src/main/java/ghidra/app/util/bin/format/pdb/DefaultCompositeMember.java