No, only one WAP allowed. But if you were (are) prepared to run that extra ethernet cable that far, why not just connected it directly to that wireless receiver so that it simply becomes a wired receiver? Plug that ethernet cable into the wireless' Network socket. Reboot the gateway (maybe WAP too), and you should be good to go.
Of course if you have 2 tv's "up there" you would need yet another ethernet cable for it.
Another possibility, use that long ethenet cable to the existing WAP to give you more freedom to move it around to possibly find a better place to allow its signal to reach all the wireless receivers.
This is a public forum and I am a customer just like you. Click kudo if you feel this post is helpful and "Accept as Solution" if it solves your problem.
Award for Community Excellence 2019 Achiever* *The views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.