This is covered in the LHP. The circumstances when the requests can be acted on are identified and decisions made by the divine realm as to the way the request is acted upon in a given instance. There are complications with disrupting pregnancies, for example, but the functional aspects of hybrids are another story and the functioning of clones, so when these are already present in the human environment there can be consequences should there be sudden failures on a large scale. This could create a backlash seeking to find the cause and carry out retribution, so this is a further consideration that will be factored into what the divine will do to alter intentional manipulations by the Extraterrestrial Alliance. So there are practical limits that must be considered in making dramatic alterations of the alien plans, but you can be sure we always have human needs first and foremost in our thoughts as we act on all Protocol requests.