Twelve West Coast players trained with East Perth this week in preparation for the second semifinal against Subiaco.
Twelve established Royals also took part in the lively training session at Medibank Stadium on Wednesday night.
Fitting 24 fit, keen and committed players into 22 places will provide coach Brian Dawson with one of his greatest challenges since he took on the role last year.
"Somewhere between nine and 12 (Eagles) will be available," Dawson said.
"We don't know exactly yet. It is good to have them around."
Subiaco coach Jarrad Schofield anticipated that 12 Eagles would play on Sunday.
"They have averaged 12 a week and if they play up to 12 that will be great for them," he said.
"We have a pretty good idea on who will come back."
Fifteen Eagles had qualified and were available to play finals for the AFL club's affiliate and each one told West Coast they were eager to play for East Perth.
But big men Scott Lycett and Jeremy McGovern were held out because of their long-term strategic value to the Eagles while Simon Tunbridge, who was a late withdrawal from the last home-and-away game, did not train this week and is unlikely to be considered. Fraser McInnes is the only Eagle to play all 20 WAFL matches this season and he was guaranteed his place on Sunday when the tribunal dismissed a rough-conduct charge against him.
Tough midfielder Pat McGinnity ran a series of hard laps, defender Blayne Wilson jogged several easy ones and Jacob Brennan was an onlooker.
Sam Butler, who will attempt to add a WAFL flag to his 2006 Eagles premiership, Josh Hill and Dom Sheed all returned after being part of the recent West Coast campaign while Adam Carter, Ash Smith and Brant Colledge have been Royals regulars for much of the season.
The greatest pressure is on young utility Dylan Main who has played five senior matches but may be one of the players to make way for the more experienced group.
Versatile defenders Kyle Anderson and Nathan Blee are also available and are set to return to action as part of East Perth's home-grown cohort.
East Perth used their most inexperienced team in three seasons in the loss to Claremont last Saturday with six players who had made four or fewer senior appearances.
Another three had played no more than 15 games. They could regain 791 matches in AFL and WAFL experience on Sunday.