In the event that the decree (of which many are here) proposes actions that are opposed by those parishes, then the process to be followed is shown in this case history.... (with further information here and canon law)
I have already exercised my canonical rights first according to the norm of can. 1734 to petition Archbishop Cushley for the revocation of Decree 12/18 and subsequently, following the rejection of my petition by Archbishop Cushley, according to the norm of can. 1737 to make hierarchical recourse to Beniamino Cardinal Stella, Prefect of the Congregation for the Clergy. As a result, the execution of decree 12/18 has been suspended until the hierarchical recourse is decided - perhaps in 2 years' time.
Having had contact from a number of other parishes wishing to stop their own parishes being merged and then in one case closed, I am concerned that very few people understand the process that needs to be undertaken.
For example, some parishes think that if they have a meeting with the Archbishop and express their disquiet he will listen and not merge their parishes. Unfortunately, that is not a process that will work and, in following such a plan, the parishes are most likely to miss the very tight deadlines set out in canon law (but not mentioned in the decrees) for individuals to exercise their rights according to the norms of cann. 1734 & 1737.