Faith Hill and Tim McGraw would no doubt love to become grandparents in the future - but for now they have a 'grandpuppy'!MORE: Faith Hill's daughter Audrey McGraw shares images from romantic photoshoot - and they're stunningThe celebrity couple's oldest daughter Gracie McGraw took to Instagram over the weekend to share a series of pictures of herself posing with her beloved pet dog, who she referred to as her son.The duo were pictured inside Gracie's stylish New York apartment, which features an opulent lobby. In the caption, the talented singer simply wrote: "Quiet day out with my son."VIDEO: Faith Hill and Tim McGraw's love story Fans were quick to comment on the post, with one writing: "Enjoy your day out with your son!" while another wrote: "What an adorable dog." A third added: "He's gorgeous!"MORE: Audrey McGraw shows support for big sister Gracie in the best wayMORE: Tim McGraw & Faith Hill's model daughter Audrey wows in dreamy backless topGracie is the oldest of Faith and Tim's daughters, and moved to New York last year to pursue her dream as a Broadway performer.She's doing an incredible job, and is currently performing in Broadway Sings.