Judge Tyrell was born in Ireland. 1790 Seems to have had several wives, so these boys could have been grandchildren of his from an early marriage. Tyrell and his wife Georgiana living Salcombe Regis, & St Leonard Exeter.
The Tyrell line seems to come from Ireland, picked up another name John Tyssen Tyrell given the unusual middle name, might be worth working that one.
Pleased to have been able to help a bit. Will keep my eyes open!!