BaCu2Ge2O7 is reported to be a one dimensional Heisenberg antiferromagnet, with three dimensional long range order at low temperatures due to small antiferromagnetic interactions between the chains. These inter-chain interaction are tuneable by substituting Ge for Si. At complete substitution, BaCu2Si2O7 also orders, but the inter-chain coupling is ferromagnetic. We propose to survey the BaCu2(Si1-xGex)2O7 phase diagram, to investigate the consequences of tuning x to minimize inter-chain coupling, through competition between ferro- and antiferromagnetic inter-chain couplings. BaCu2(Si0.5Ge0.5)2O7 may represents a rare example of a S=1/2 system with tuneable inter-chain interactions and consequently provide a useful model system for probing the fascinating phenomena observed in 1D quantum magnetic systems and the complex interplay of competing intra- and inter-chain interactions