Baptism of child with part member family

I haven't had this exact experience, but we have had a number of weddings in which we wanted to include our all non-member extended family. My uncle and his children are very musical and they performed some beautiful spiritual pieces of music, and my aunt and her daughter are very good cooks so we invited them to be in charge of the cake. Maybe for the baptism, if your parents want to participate they could choose and read some scripture passages about Chirst and baptism, and share a thought about their faith in Christ. This is also something you can discuss with your bishop, he might have some good suggestions. Involving family in the important life events of our children, even when their beliefs differ from ours, can really enrich those events, and bring an increase of love, understanding and harmony to our families.

I am LDS; my husband is not. We do this fine bit of choreography any time our children take on covenants in the LDS church. :) We choose to have the non-LDS side of the family participate as fully as possible, and it seems to work very well.

For instance, when our son was baptized, the LDS grandparents gave him a Book of Mormon/D&C; his Catholic grandmother gave him a nice LDS/KJV Bible. With our next child's baptism, we're planning to have 5×7 sheets of paper and pens/colored pencils available for everyone in attendance to write a note to her while she's dressing, with a special thought, their testimony, a remembrance of their own baptism, wishes for her continued spiritual growth, etc; we'll put them in her journal. Some friends did this at their daughter's baptism, and it kept a really lovely spirit present; some of the most tender notes came from non-LDS friends who were so loving and supportive, and shared beautiful testimonies of our Savior.

We also keep the whole family involved in celebrating after, with family favorite recipes and foods, and some low-key family time all together.