Pine Script Custom development

We commonly have many watchlists of stocks. If I have a watchlist of, say 30 stocks, and want to compare them with price of a pre-determined asset, say SPY, is there a script that can do this function? For the one “Ratio Between Two Symbols”, we need to manually input two symbols each time. Is it possible to set the 1st symbol automatically to be the symbol whatever I choose on the watchlist, and the 2nd symbol be the pre-determined symbol, like SPY. If possible, it would be very convenient to just choose up and down in the long long watchlist of stocks and see their price ratio trend with a benchmark asset like SPY quickly. Many thanks.


You can see, in the top panel, is IBB, the lower panel is IBB/SPY.

The watchlist has IBB and KRE, next I want to click on KRE but have the lower panel (chart) change to KRE/SPY while the top chart only display KRE.