At this point since it's after the fact while not totally correct; you may explore adding the missed asset/basis amount as a selling cost to just reduce your gain. 

Given that the property was worth $390K in its current condition, I saw an opportunity to make the numbers work while keeping my upfront costs low.Instead of increasing my cash offer, I negotiated a $25K down payment with the seller carrying the balance for two years through owner financing.

Still cracks me up. 

We were working with this agent early last year and signed an exclusive buyer agency agreement that expired June of last year.

If you move your expectations to keeping some money in, but refinancing out as much as you can then you'll be set up to not be let down from the jump.

Giving up $100k+,in tax free income.

We have just signed the promissory contract on a place in Peniche.

Do not get excited about getting a low offer signed by the seller as the lenders valuation will be the ultimate determining factor of approvable sale price. 

When I inquired about it, plumber said lining, it is usually not prefect since this is PVC breakage not just pipe cracks and the cost saving is not significant enough and maybe headache down the road.I will try to get more quotes and maybe a company that specializes in pipe lining options.I was told foundation work / under slab pipe repair is common in the Dallas TX area due to soil type.

This can be very expensive and is usually the worst choice because you can't justify the cost.2.