Getty / Savannah Lee Blackstock Composite

Brandon Blackstock was fighting a difficult cancer battle before his death ... but, you could hardly tell a couple weeks ago when he was grinning big in a photo with his daughter.

Savannah Blackstock Lee , Brandon's daughter from his first marriage to Melissa Ashworth , shared a photo on Facebook last month standing alongside her dad with a sprawling wilderness behind them ... and, Brandon's arm is slung over her shoulder. Savannah Lee Blackstock

Blackstock's got his Uggs on ... bringing his leg up on a bench Captain Morgan-style. Savannah's totally beaming in the pic -- and, from the outside, it seems like nothing's wrong. She captioned the picture, "Back home to the mountains & my daddy."

The pic was posted to FB on July 20 -- and,

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