Hello PaulaF,
Welcome to the community!
Firstly, you should note that the Fido Roam charges will incur if your phone uses services -- make or receive a call, send a text message or use data abroad. If you did not wish to use Fido Roam, you would need to opt-out of the feature. In doing so, any usage would be on a pay-per-use basis. You can view those rates in the link provided above. If you wished to opt-out of Fido Roam, you would need to contact customer service. In addition, they can also be contacted via Live Chat, Facebook, or Twitter. Those methods can be accessed via the contact page posted above.
It should be mentioned that while receiving SMS would not incur the roaming charge, any data contained within MMS (incoming or outgoing) would be considered roaming data and charged accordingly. You should note that MMS are not solely restricted to pictures or video messages. Messages with subject headers or group messages etc are also considered MMS. It should further be noted that iMessages and RCS messages are sent (and received) as data and not as text messages (SMS). Even if the text message received is SMS, if your device is configured to provide Delivery and/or Read receipts, those would be sent as SMS and considered roaming usage.
In order to prevent unintended roaming charges, it is generally recommended to disable data and roaming data. However, you should note that disabling those settings does not prevent roaming for voice and messaging. In addition, some manufacturers might allow some data usage to occur despite those settings (see here). That's why it is also generally recommended to enable Airplane and/or Flight modes in order to prevent unplanned roaming usage. You could then manually enable Wifi when required.
That said, I do understand wanting your daughter to be able to text while using Wifi at the resort. Unfortunately, text messages (SMS and/or MMS) do not generally transmit via Wifi. Be that as it may, if her phone and plan are supported for Wifi-calling, that feature may allow her to do so.
However, it should be noted that while using Wifi for regular internet access will not incur Fido Roam charges, there seems to be some misunderstanding regarding Wifi-calling . I'm not sure how people have gotten the impression that Wifi-calling does not use the networks. However, that is not true. While the calls and messages do not transmit via cellular towers, they still use the networks via the internet gateway (see image here). The cellular towers and Wifi are merely alternate means of accessing the networks. Calls and messages would not be able to complete or get sent/received without the networks. As such, using Wifi-calling is technically using Fido services. Having said that, they have allowed certain usage to be free from additional charges. All the messages and calls received (from anywhere in the world) will be taken from a plan's voice minutes and messaging limits. As well, all Wifi-calling messages and calls made to a Canadian phone number while abroad won't incur long-distance or roaming charges (see link above).
So, it could be possible for her to text message while using Wifi at the resort without incurring roaming charges. You would need to ensure her device does not connect to local cellular towers (ie enable Airplane or Flight mode) and she only messages Canadian phone numbers (assuming Wifi-calling is supported on her phone and plan).
Hope this helps 😀
Cheers
