Hi. If either parent finds the current schedule no longer is workable due to a job change, the first thing the court expects is that you try and reach agreement to make some changes - eg swap a day each week or vary the times. If it's just, say, to swap a wednesday tea time to a Thursday tea time, then as long as you both agree in writing, that is seen as an agreed variation. In writing can be as simple as a text or email just saying - agree to swap Wednesdays for thursdays for now due to your change of working hours. And the other parent just respond with - thanks that's fine or whatever.
If it's going to need fairly major changes - due to shift work, different week-ends etc, then you can still agree the changes between you, but it's advisable to get a solicitor to draw up the changes and submit them to court saying the parties have agreed to vary the order as follows, by consent.
In a way it's a waste of court time and funds to go back just to change a schedule to a different one. But if the number of nights will be different or you can't agree a child focused schedule that works around work commitments, then it may need an application to vary.
Hope that helps. The court expects parents to try and resolve things though, as lives do change sometimes - and jobs.
What exactly is the situation? Are you saying there's an order for Friday to Sunday every other week-end and a midweek tea time and the other parent is saying they can't do that any more? If so, what are they suggesting instead? And then we can maybe comment if that sounds reasonable or not.
It doesn't matter which parent it is, or whether the parent wishing to make the changes is the one the child lives with or the one the child spends time with. But parents are expected to try and resolve issues like that if possible. Most orders have a clause that says "such further and other times as agreed between the parties". So providing it's agreed in writing, it's fine.