The same evening of the morning Charlie accompanies Frank to the tram stop, how does he modify his request to take the children to England?

The same evening he accompanies Frank to the tram stop, Charlie repeats his offer. He suggests that Frank is hesitant regarding him taking the children because he thinks Charlie will have trouble managing them on the trip. Charlie then suggests that the solution is for Lisa Ivanovna to come with them. After running several scenarios through his mind, all of which seem ridiculous, Frank finally says he does not know quite how to explain it to Lisa. Charlie has not even asked the children, so the matter is dropped.