How appropriate is it for us to get involved with our child’s mom making another adoption plan?

Our children (ages 2 1/2 and 22 months) have the same birth mother. After our son was placed with us at birth, she became pregnant again and asked us to adopt a second baby.

She told us this past Spring that she was once again pregnant. She recently asked us if we would like to adopt a third baby. For a very long list of reasons which I do not feel comfortably detailing here, we have decided it is not appropriate for us to adopt another baby.

She has asked if we could help her to find another adoptive family. We do not feel it is appropriate for us to be involved in actually selecting another family to adopt this baby. We feel that would be “crossing a boundary.”

She has asked us to at least recommend a few agencies. What do others think? Would this be appropriate? Or is this also crossing a boundary?

If appropriate, could anyone recommend a reputable agency who could help her find another adoptive family? She is currently living in the Greenville, SC area and does not wish to work with an agency that is “Christian-focused.”

Also, is it appropriate for us to say that if whomever she chooses is comfortable with it, would it be possible to have an extended open adoption so that the siblings could have a relationship?