When building a team, the players who are eligible in two positions can be useful.
The best move is usually to put the defender/midfielder or forward/midfielder into the back or forward line, that way your team is effectively playing extra fantasy midfielders, and midfielders are the ones that bring in the stats.
The defender/forward fantasy football player can be played wherever the fantasy coach wants. If you want more goal-kickers, then adding a player who is a forward in the AFL and also position eligible as a defender in fantasy AFL will work. You can also consider team balance when deciding if the player is a forward or defender. If you already have 5 star fantasy forwards, and your back line isn't as great, switch your player from the forward to the back line.
A forward/ruckman will probably help more in the ruck spot. As goals bring in more fantasy points than hitouts.
Defender/Midfielder
(HAW) HODGE, Luke
(CAR) SCOTLAND, Heath
(WCE) EMBLEY, Andrew
(HAW) LADSON, Rick
(PTA) BURGOYNE, Peter
(PTA) CORNES, Chad
(COL) LOCKYER, Tarkyn
(ESS) HOULI, Bachar
(KAN) FIRRITO, Michael
(BRL) ADCOCK, Jed
(COL) MAXWELL, Nick
(STK) CLARKE, Xavier
(GEE) ROOKE, Max
(COL) COOK, Ryan
(SYD) BARLOW, Ed
(COL) TOOVEY, Alan
(WCE) DAVIS, Ryan
(PTA) STEWART, Paul
(PTA) FARMER, Mitch
(MEL) PETTERD, Ricky
(BRL) HANLEY, Pearce
(FRE) HILL, Stephen
(PTA) BROADBENT, Matthew
(SYD) O'KEEFE, Daniel
(PTA) LAURIE, Jesse
Forward/Midfielder
(KAN) HARVEY, Brent
(ADE) GOODWIN, Simon
(RIC) DELEDIO, Brett
(RIC) RICHARDSON, Matthew
(COL) DAVIS, Leon
(BRL) BRENNAN, Jared
(ESS) LOVETT, Andrew
(WBD) HILL, Josh
(MEL) SYLVIA, Colin
(HAW) OSBORNE, Michael
(HAW) DEW, Stuart
(WCE) STAKER, Brent
(HAW) MORTON, Jarryd
(FRE) SOLOMON, Dean
(CAR) BENTLEY, Greg
(RIC) EDWARDS, Shane
(HAW) MCGLYNN, Ben
(WBD) HIGGINS, Shaun
(ESS) SKIPWORTH, Hayden
(KAN) ZIEBELL, Jack
(COL) SIDEBOTTOM, Steele
(BRL) AUSTIN, Matt
(FRE) WALTERS, Michael
(SYD) GILCHRIST, Taylor
(MEL) HEALEY, Rhys
Ruck/Forward
(KAN) PETRIE, Drew
(STK) KOSCHITZKE, Justin
(ADE) MORAN, Brad
(FRE) BRADLEY, Kepler
(BRL) CLARK, Mitch
(ADE) TIPPETT, Kurt
(WBD) SKIPPER, Wayde
(RIC) VICKERY, Tyrone
(PTA) LOBBE, Matthew
(ADE) SELLAR, James
(HAW) WALSH, Tim
Ruck/Midfielder
(FRE) GILMORE, Daniel
Ruck/Defender
(STK) BLAKE, Jason
(PTA) TRENGOVE, Jackson
Defender/Forward
(WCE) WIRRPANDA, David
(FRE) MCPHARLIN, Luke
(CAR) WALKER, Andrew
(HAW) BROWN, Campbell
(ESS) MCPHEE, Adam
(KAN) MCMAHON, Scott
(COL) COX, Shannon
(RIC) SCHULZ, Jay
(SYD) GRUNDY, Heath
(BRL) MCGRATH, Ashley
(CAR) HOULIHAN, Ryan
(KAN) HANSEN, Lachie
(KAN) ROSS, Ben
(WBD) TILLER, Stephen
(BRL) HENDERSON, Lachie
(CAR) HARTLETT, Adam
(STK) ALLEN, Jarryd
(ADE) DAVIS, Phil
(HAW) SCHOENMAKERS, Ryan
(HAW) LISLE, Jordan
(ADE) MCKERNAN, Shaun
(ADE) SLOANE, Rory
(BRL) TYLER, Matt
(ADE) HENDERSON, Ricky
(ADE) DONNELLY, Brian
(BRL) GARNER, Pat
(STK) HARETUKU, Khan
(GEE) LAIDLER, Jeremy
(SYD) MURPHY, Brendan
(FRE) SHEPHEARD, Hamish
(WCE) WILSON, Callum
(MEL) ZOMER, Trent