Demand both of them

"I told you before that I am more interested in your daughter. She is a young pretty little thing and I've never had the pleasure to taste a virgin. I cannot be sure that the resulting bastard will be mine if I were to bed you." you shaked your head refusing her offer.

"Please milord, I had my monthly flow just five days ago. I am not pregnant now and you can still plant your seed in me if it is your wish to do so. You can ask Maris our maid if you don't believe me, she was washing my petticoat." she replied in shame.

"It is either both of you or we have no agreement. I will let you stay the mistress of this estate with all your former rights and authority until I find myself a proper wife. Do not overestimate your worth milady. Now please lead me to your bed to seal the deal." you ordered impatiently.

She was not in any position to refuse you offer and knew it was impossible to change your mind. She wispered something to Lili's ear and hugged her before turning to you, "Please follow me milord. I will guide you to our bedchamber."