Hi Noah,
My name is Isaac Carbajal, I'm a producer and audio /mix engineer in Mexico. The fact of playing piano, guitar and some violin make the artistic side easy for me. While I'm can't help you too much with the writing process, I specialize in arranging and producing pop music. Mixing is my biggest passion and can get your project done with high level audio quality. I can program midi sequences and I am proficient in Logic, Melodyne and Pro Tools software.
As you are planning to develop this project with 2 producers, I'd suggest to make a calendar or Gantt chart with every task and assign responsibles for each. Assuming you will be requiring musicians and a singer, I'm proposing to spend 2 weeks composing and making arrangements, one week recording and one week for mixing, adjustments and Mastering. As I have more information about the project we can fine tune dates.
I would be happy to contribute to you and your grandfather's project. If you need any references /work samples please let me know.
Regards,
Isaac Carbajal