Note sure if the OP is still interested, but to answer some of her queries, which are in any case relevant to some other posters.
- As the Glascotts/Glasscotts were landed, a search of the records of the Registry of Deeds is pretty much essential. It was previously possible to examine these in person in Dublin, not sure if that is still so. The LDS have microfilm copies that can be ordered/examined at their Family History centers. However, they are difficult time consuming and expensive. A professional researcher may be the way to go (one familiar with the Registry of Deeds!).
-However, as the name implies, the Registry of Deeds exists to register documents such as deeds, leases, mortgages, etc. An inheritance which did not involve such a document would not normally be recorded.
- The family appear extensively in the
* Prerogative Wills Index
* Ferns Will Index
* Ferns Marriage Licence Bonds index
For example, the will of a John Glasscott of Alderton (i.e. Pilltown) was proved in 1811 in the Prerogative Registry, while the marriage of Rev. William Glascott is in the MLB index.