I did find that it is possible to claim as per Sage v. Sage, 2014 ONSC 1330 (CanLII), <https://canlii.ca/t/g5fgm>, retrieved on 2022-03-28
It is generally not accepted unless a series of factors warrant its consideration such as:
(a) Why is the child care service necessary?
(b) Is it in the best interest of the child for child care services to be provided by the family member?
(c) Was child care provided by the family member prior to separation?
(d) Did the family member receive any compensation for child care services provided prior to separation?
(e) Will the child care services be provided solely by the family member or will there be other persons assisting with the activity?
(f) Will the family member provide child care services as part of normal, inevitable, family interaction or do special arrangements have to be made to facilitate the activity?
(g) Is the family member foregoing employment or other activity to provide the child care?
(h) Is the provision of child care the dominant activity or is it ancillary to normal, inevitable family interaction?
(i) Does the family member have some special child care qualifications?
(j) What type of child care services will be provided? Will the services be the same as a structured day care service or will the service be similar to a babysitting service?
(k) Will the provision of child care service be the dominant service or will it be intermingled with caring for other family members?
(l) How were the amounts charged for child care expenses arrived at? Is it based on speculation or based on some objective basis?
(m) What is the nature of the financial relationship between the parties?

Given the nature and circumstances of the family relationship, is financial compensation a reasonable expectation?
(o) Are the time periods for which financial compensation is expected defined or open-ended?
(p) Are the child care expenses claimed reasonable in all the circumstances?
(q) What is the ability of the parents to pay for the child care expenses?