Eh!?
You're letting me have the bigger piece...!?*Awaiting headpats~Hey,
Can we sleep together today?Onii(nee)-chan.Seems the type that would oblige if you said, "I want you to call me this!".
Being called by name is also an option.Little SisterS-So, um...
Weeell...I have a favor to ask...I want you to feed it to me.Nii(Nee)-san.Which do you prefer?