With proper and advanced planning you certainly can structure an Exchange so that you have the replacement property lined up and ready to be purchased prior to closing on your sale.Another option, if you do not want to actively manage property or you want a "safety net", would be to identify a DST (Delaware Statuary Trust).

@Bradley De comarmond provide signed leases and rent rolls to the appraiser. 

Basically, arrive at a way to de-risk the deal closing for the seller.  

If the address still doesn't work then chances are it is in a different town that borders the one you were doing it in.

Good tip.The last deal I bought was a single family house in Westerville Delaware County, highly desirable suburb for families. 

All 3 are in Delaware County, PA (SE of Philadelphia) I found 2 of my properties via Fannie Mae and HUD.

.- Similarly, if you set up a CDN holding company and it owns the houses or LLC, again full income taxes are paid on both sides of the border.- Putting the properties in a US 'C' corp (with LLC's or not) gives you the flexibility to decide when profits from the 'C' corp are repatriated.

My fiancé  and I live on Eastern shore in DE.

I am looking to find a mortgage broker that is familiar with real estate investing in the Wilmington DE area.  

You're not going to find a 6 unit, mixed use, that a VA appraiser or a residential lender are going to bite on and deeper than that, if you eventually do find the right deal, the right lender who has the right appraiser and right DE underwriter, you would have stepped over so many dollars to get to those dimes, it won't be worth it.