As people's communication becomes digital, text-based digital messages effectively help to connect families living apart from each other. However, aged parents who have difficulties using smartphones have higher chances to be excluded from digital communication within their family members, making it challenging to communicate smoothly. In this paper, we went through Research through Design process by developing three Birdy prototypes: interactive artifact supporting aged parents' digital messaging with their grand-/children through scanning handwritten paper messages and printed emojis. The result of our three-week in-field study with six pairs of family participants revealed that Birdy helped aged parents to engage in digital communication actively and encouraged rich communication between aged parents and their grand-/children. Additionally, we identified the effects and roles of paper and handwriting in digital communication. Our findings proposed designing systems for the elderly's digital and intergenerational communication and suggested new analog-digital messaging methods for affective communication.