Gwen Stefani and Blake Shelton are acting as a family as they reportedly prepare for a Christmas wedding.

According to a new report, Stefani and Shelton recently enjoyed a private tour at the Cincinnati Zoo & Botanical Garden, where a source claimed Shelton appeared to be playing a major role in the lives of Stefani's three sons, Kingston, 10, Zuma, 7, and Apollo, 2.

"They really did look like a family," an onlooker told Life & Style. "Blake acted like he was Apollo's dad."

Since Stefani and Shelton's relationship began last fall, they have spent tons of time with Stefani's kids and just weeks ago, they were spotted together at Shelton's ranch in Oklahoma.

Although Stefani and Shelton haven't yet confirmed plans to tie the knot, rumors have been swirling in regard to the future event and according to the magazine, all three of Stefani's sons will have roles in the potentially impending nuptials. 

“Apollo wants to be the ring bearer, and the two older boys will be junior groomsmen with Blake," an insider explained. "Blake wants it to be really special, to show them coming together as a family.”

The source went on to reveal that Shelton, who is currently in the midst of production on The Voice Season 11, will be paying for the entire wedding ceremony, which will reportedly be limited to family and close friends of the superstar couple.

To see what Shelton had to say about his life with Stefani and her music, check out his interview with Seth Meyers below.

Tags: Gwen Stefani Blake Shelton