I have done similar to create a āVWLR ex-USā (something I cannot buy from Vanguard). The percentages match current weightings and OCF comes to 0.13%, compared to VWRLās 0.22%. I do not intend to make adjustments if the weighing of a componemt, say Japan, in VWRL changes by small amount, I will review in a year.
To permit users to more closely replicate the operation of an ETF there would need to be an option to āpurchase/sell proportionally by sharesā. ie to increase/decrease the number of shares owned in each slice of fhe pie by the same percentage.