Is it possible to seller finance an appraisal gap? (Ideas to cover the gap!)

[Daniel Gibson]

Hi BP,

I'm looking to purchase a property (offer accepted at $485k) however the appraisal came in $30k under ($455k) which I'm unable to cover. The seller (so far) isn't budging and has refused to lower the purchase price. 

A few questions: 

1. Has anyone ever seller finance the the appraisal gap?

2. Beyond submitting alternative comps to the appraiser and seller financing the gap, does anyone have any other tactics to help close the gap or cover it?

For context, the property is a 3 bed, 3 bath and interestingly, although the other 3 comps have sold recently, in the same area (>1mile radius) and had similar sqft, they were all 3 bed, 2 baths...I'm wondering whether this is grounds to push back on the appraisal? 

Within the property I'm looking to purchase, there's also an attached ADU with a full kitchen, full bath, and bedroom, which I intend to rent out. I'm wondering whether appraisers take the earning potential into consideration when assessing the value?

A HUGE thank you to anyone willing to share any knowledge, tips, tricks of the trade.

This would be property #3 but the first I've encountered where the appraisal is less then the offer price.

Gratefully, 

Dan