Administration of NRBDT

If Spouse 1 dies leaving a NRBDT in their Will and residue to Spouse 2, will the appropriation of a share of the family home into a NRBDT, completed within 2 years of death be construed by HMRC as being an IPDI for Spouse 2 and read back if completed within 2 years of S1’s demise? It was mentioned this could be the case in a seminar I recently attended… If so, if you wait 2 years to ensure the reading back provisions can’t apply, would the value of the property be based on the value when appropriated into the NRBDT, or the value of the property when S1 died? ie. is another valuation needed at this point