Realistic Photo Integration

I need a high-resolution photo of my son edited into a high-resolution photo of me with my late grandfather. The final image should maintain the original background of the photo with my grandfather.

Requirements:
- Expertise in photo editing and manipulation
- Ability to seamlessly integrate images for a realistic look
- High attention to detail

Ideal Skills:
- Proficiency in Photoshop or similar software
- Experience with high-resolution photo editing
- Strong portfolio showcasing similar work

Please ensure the final image looks natural and cohesive.