Is it permissible to slaughter the Udhiyah secretly in Belgium, given the risk of a fine, or is it better to send the money to my father to slaughter it in Morocco?

It is permissible to appoint an agent for the purchase and slaughter of the sacrificial animal (Uḍḥiyah), even if it is in a country other than that of the sacrificer. You can send the price of the sacrificial animal to your father in your home country so that he may slaughter it on your behalf, to avoid the harm and hardship that might result from hidden slaughter.

Scholars have differed regarding appointing a Christian to slaughter the sacrificial animal. Some did not permit it, while others permitted it with a degree of dislike (karāhah). The cautious approach is not to appoint Christians for the slaughter but to appoint a Muslim in your country. It is also not advisable for you to perform the slaughter yourself to avoid harm.