The actress, who made her on-screen exit from Albert Square as Jane Beale in January, now plays English teacher Christine Mulgrew on the school drama.
The 43-year-old told Inside Soap: "I want Linda Henry to come in and play my sister - I'm sure she could get a few months off EastEnders!"
Henry's Walford alter ego Shirley Carter has been at the centre of Heather's murder storyline since March, finally unmasking Ben Mitchell as the killer in yesterday's (August 15) episode.
However, EastEnders told Digital Spy earlier this month that Henry would only take a "very short" break following the plot.
"It's been lovely recently because we've had Zoe Lucker (Vanessa Gold) on Waterloo Road for a bit," she commented.
Waterloo Road returns to BBC One on a new day of Thursday on August 23, and in a new slot of 8pm.