Group Photo Enhancement

I am hoping someone can add my mother into a group photo from our wedding. For context, she was at the wedding and we have several photos of her in smaller groups, but we took a large group photo on a set of stairs that my mother missed as she was settling her parents into their room... (Budget: £10 - £40 GBP, Jobs: Adobe Lightroom, Adobe Photoshop, Image Processing, Photo Editing, Photo Retouching, Photography, Photoshop, Photoshop Design)