If there is a Child Arrangements Order and the other parent is not adhering to the terms then they are technically in breach of the order. However; a parent is able to go against the terms of a Child Arrangements Order if there is a reasonable excuse. A common reasonable excuse is if there is a safeguarding concern (harm could come to the child).
The Coronavirus is a fairly unprecedented occurrence and the courts have had to grapple with a fairly novel situation. The President of the Family Division issued some guidance on this situation and you can read this for yourself here: https://www.judiciary.uk/announcements/coronavirus-crisis-guidance-on-compliance-with-family-court-child-arrangement-orders/.
As you can see from the guidance, parents are being given a lot of discretion. It is hoped that parents will use their best judgment and only make decisions in the interests of the child and not use this situation to their advantage however.
In principle, if a parent is stopping contact due to a genuine COVID-19 safeguarding concern then the court is likely to "excuse" this breach. The court is going to be slow to punish a parent who is doing their best for their child.
So yes, if your daughter thinks that sending their child off to contact with their father puts the child at risk then this may be justified so long as it is a genuine concern.
Try to engage in some dialogue with the other parent if you can first. If they have genuine concerns then try to "think outside the box". Can contact take place via video calls etc instead? Could the other parent go out with the child to the park etc rather than take them home. Court orders are made without the foresight of these types of events so sometimes you have to agree between you different arrangements. So long as you both agree variations that is fine.
If they need help discussing this and want to try some mediation there are some services available. This site is recommended at the end of the President’s guidance I sent you the link for above: https://www.nfm.org.uk/new-service-co-parenting-through-the-coronavirus-crisis/. It is a form of mediation to assist parents to mediate over Covid-19 arrangements. It takes place remotely.
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