Cassy was still quite sensitive and didn't even notice that Lisa's finger was still inside her wet snatch until she felt it moving again. It caused her to gasp which was replaced by another moan when her stiff nipples got sucked all of a sudden. How could something wrong feel so right? The young teenager was bombarded by confusing emotions and just went with the flow of hat was happening. "Yes...I want more..." Her voice was barely a whisper and yet loud enough to be heard in the silence that had spread in the house. Maybe their mother would join them, leave or just keep standing there and continue watching her daughters exploring each others naked bodies. Cassandra's hands began to move towards her sisters chest to feel the soft flesh of another girls breasts against her curious fingers before the wandered down her sides and back to Lisa's ass again. Another orgasm was building up inside her and she wanted to make her sister feel good too, but didn't know how and tried to copy her by sliding a finger into her wet pussy too. They were now fingering each other right in front of their mother, like they had forgotten that she was even there.